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Sample records for aerosol mass fractions

  1. Analysis of laser-produced aerosols by inductively coupled plasma mass spectrometry: transport phenomena and elemental fractionation.

    PubMed

    Koch, J; Wälle, M; Dietiker, R; Günther, D

    2008-02-15

    The transport phenomena of laser-produced aerosols prior to analysis by inductively coupled plasma mass spectrometry (ICPMS) were examined. Aerosol particles were visualized over the cross section of a transport tube attached to the outlet of a conventional ablation cell by light scattering using a pulsed laser source. Experiments were carried out under laminar or turbulent in-cell flow conditions applying throughputs of up to 2.0 L/min and reveal the nature of aerosol transportation to strongly depend on both flow rate and carrier gas chosen. For instance, laser ablation (LA) using laminar in-cell flow and helium as aerosol carrier resulted in stationary but inhomogeneous dispersion patterns. In addition, aerosols appear to be separated into two coexisting phases consisting of (i) dispersed particles that accumulate at the boundary layer of several vortex channel flows randomly arranged along the tube axis and (ii) larger fragments moving inside. The occurrence of these fragments was found to affect the accuracy of Si-, Zn-, and Cd-specific ICPMS analyses of aerosols released by LA of silicate glass (SRM NIST610). Accuracy drifts of more than 10% were observed for helium flow rates of >1 L/min, most probably, due to preferential evaporation and diffusion losses of volatile constituents inside the ICP. The utilization of turbulent in-cell flow made the vortex channels collapse and resulted in an almost complete aerosol homogenization. In contrast, LA using argon as aerosol carrier generally yielded a higher degree of dispersion, which was nearly independent of the flow conditions applied. To illustrate the differences among laminar and turbulent in-cell flow, furthermore, the velocity field inside the ablation cell was simulated by computational fluid dynamics. PMID:18205331

  2. Oxygenated fraction and mass of organic aerosol from direct emission and atmospheric processing measured on the R/V Ronald Brown during TEXAQS/GoMACCS 2006

    NASA Astrophysics Data System (ADS)

    Russell, L. M.; Takahama, S.; Liu, S.; Hawkins, L. N.; Covert, D. S.; Quinn, P. K.; Bates, T. S.

    2009-04-01

    Submicron particles collected on Teflon filters aboard the R/V Ronald Brown during the Texas Air Quality Study and Gulf of Mexico Atmospheric Composition and Climate Study (TexAQS/GoMACCS) 2006 in and around the port of Houston, Texas, were measured by Fourier transform infrared (FTIR) and X-ray fluorescence for organic functional groups and elemental composition. Organic mass (OM) concentrations (1-25 μg m-3) for ambient particle samples measured by FTIR showed good agreement with measurements made with an aerosol mass spectrometer. The fractions of organic mass identified as alkane and carboxylic acid groups were 47% and 32%, respectively. Three different types of air masses were identified on the basis of the air mass origin and the radon concentration, with significantly higher carboxylic acid group mass fractions in air masses from the north (35%) than the south (29%) or Gulf of Mexico (26%). Positive matrix factorization analysis attributed carboxylic acid fractions of 30-35% to factors with mild or strong correlations (r > 0.5) to elemental signatures of oil combustion and 9-24% to wood smoke, indicating that part of the carboxylic acid fraction of OM was formed by the same sources that controlled the metal emissions, namely the oil and wood combustion activities. The implication is that a substantial part of the measured carboxylic acid contribution was formed independently of traditionally "secondary" processes, which would be affected by atmospheric (both photochemical and meteorological) conditions and other emission sources. The carboxylic acid group fractions in the Gulf of Mexico and south air masses (GAM and SAM, respectively) were largely oil combustion emissions from ships as well as background marine sources, with only limited recent land influences (based on radon concentrations). Alcohol groups accounted for 14% of OM (mostly associated with oil combustion emissions and background sources), and amine groups accounted for 4% of OM in all air

  3. Tropopsheric Aerosol Chemistry via Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Worsnop, Douglas

    2008-03-01

    A broad overview of size resolved aerosol chemistry in urban, rural and remote regions is evolving from deployment of aerosol mass spectrometers (AMS) throughout the northern hemisphere. Using thermal vaporization and electron impact ionization as universal detector of non-refractory inorganic and organic composition, the accumulation of AMS results represent a library of mass spectral signatures of aerosol chemistry. For organics in particular, mass spectral factor analysis provides a procedure for classifying (and simplifying) complex mixtures composed of the hundreds or thousands of individual compounds. Correlations with parallel gas and aerosol measurements (e.g. GC/MS, HNMR, FTIR) supply additional chemical information needed to interpret mass spectra. The challenge is to separate primary and secondary; anthropogenic, biogenic and biomass burning sources - and subsequent - transformations of aerosol chemistry and microphysics.

  4. Chemical Structural Characteristics of HULIS and Other Fractionated Organic Matter in Urban Aerosols: Results from Mass Spectral and FT-IR Analysis.

    PubMed

    Chen, Qingcai; Ikemori, Fumikazu; Higo, Hayato; Asakawa, Daichi; Mochida, Michihiro

    2016-02-16

    The chemical characteristics of complex organic matter in atmospheric aerosols remain poorly understood. Water-insoluble organic matter (WISOM) and water-soluble organic matter (WSOM) in the total suspended particulates collected in the city of Nagoya in summer/early autumn and winter were extracted using multiple solvents. Two fractions of humic-like substances, showing neutral and acidic behavior (HULIS-n and HULIS-a, respectively), and the remaining highly polar part (HP-WSOM) were fractionated from WSOM using solid phase extraction. The chemical structural characteristics and concentrations of the organic matter were investigated using mass spectrometry and Fourier transform infrared (FT-IR) spectroscopy. WISOM and HULIS-n had low O/C ratios (0.1 and 0.4, respectively) and accounted for a large fraction of the organics in aerosols (70%). HULIS-a and HP-WSOM had higher O/C ratios (0.7 and 1.0, respectively), and their concentrations in summer and early autumn were on average ∼2 times higher than those in winter. The mass spectrum and FT-IR analyses suggest the following: (1) WISOM were high-molecular-weight aliphatics (primarily C27-C32) with small proportions of -CH3, -OH, and C═O groups; (2) HULIS-n was abundant in aliphatic structures and hydroxyl groups (primarily C9-C18) and by branched structures; (3) HULIS-a and HP-WSOM contained relatively large amounts of low-molecular-weight carboxylic acids and alcohols (primarily C4-C10); and (4) WISOM and HULIS-n were relatively abundant in amines and organic nitrates. PMID:26771766

  5. Analysis of the unresolved organic fraction in atmospheric aerosols with ultrahigh-resolution mass spectrometry and nuclear magnetic resonance spectroscopy: organosulfates as photochemical smog constituents.

    PubMed

    Schmitt-Kopplin, Philippe; Gelencsér, Andras; Dabek-Zlotorzynska, Ewa; Kiss, Gyula; Hertkorn, Norbert; Harir, Mourad; Hong, Yang; Gebefügi, Istvan

    2010-10-01

    Complementary molecular and atomic signatures obtained from Fourier transform ion cyclotron resonance (FTICR) mass spectra and NMR spectra provided unequivocal attribution of CHO, CHNO, CHOS, and CHNOS molecular series in secondary organic aerosols (SOA) and high-resolution definition of carbon chemical environments. Sulfate esters were confirmed as major players in SOA formation and as major constituents of its water-soluble fraction (WSOC). Elevated concentrations of SO(2), sulfate, and photochemical activity were shown to increase the proportion of SOA sulfur-containing compounds. Sulfonation of CHO precursors by means of heterogeneous reactions between carbonyl derivatives and sulfuric acid in gas-phase photoreactions was proposed as a likely formation mechanism of CHOS molecules. In addition, photochemistry induced oligomerization processes of CHOS molecules. Methylesters found in methanolic extracts of a SOA subjected to strong photochemical exposure were considered secondary products derived from sulfate esters by methanolysis. The relative abundance of nitrogen-containing compounds (CHNO and CHNOS series) appeared rather dependent on local effects such as biomass burning. Extensive aliphatic branching and disruption of extended NMR spin-systems by carbonyl derivatives and other heteroatoms were the most significant structural motifs in SOA. The presence of heteroatoms in elevated oxidation states suggests a clearly different SOA formation trajectory in comparison with established terrestrial and aqueous natural organic matter. PMID:20879800

  6. Constraining the aerosol influence on cloud fraction

    NASA Astrophysics Data System (ADS)

    Gryspeerdt, E.; Quaas, J.; Bellouin, N.

    2016-04-01

    Aerosol-cloud interactions have the potential to modify many different cloud properties. There is significant uncertainty in the strength of these aerosol-cloud interactions in analyses of observational data, partly due to the difficulty in separating aerosol effects on clouds from correlations generated by local meteorology. The relationship between aerosol and cloud fraction (CF) is particularly important to determine, due to the strong correlation of CF to other cloud properties and its large impact on radiation. It has also been one of the hardest to quantify from satellites due to the strong meteorological covariations involved. This work presents a new method to analyze the relationship between aerosol optical depth (AOD) and CF. By including information about the cloud droplet number concentration (CDNC), the impact of the meteorological covariations is significantly reduced. This method shows that much of the AOD-CF correlation is explained by relationships other than that mediated by CDNC. By accounting for these, the strength of the global mean AOD-CF relationship is reduced by around 80%. This suggests that the majority of the AOD-CF relationship is due to meteorological covariations, especially in the shallow cumulus regime. Requiring CDNC to mediate the AOD-CF relationship implies an effective anthropogenic radiative forcing from an aerosol influence on liquid CF of -0.48 W m-2 (-0.1 to -0.64 W m-2), although some uncertainty remains due to possible biases in the CDNC retrievals in broken cloud scenes.

  7. Mexico city aerosol analysis during MILAGRO using high resolution aerosol mass spectrometry at the urban supersite (T0) - Part 2: Analysis of the biomass burning contribution and the non-fossil carbon fraction

    SciTech Connect

    Aiken, A.C.; Wang, J.; de Foy, B.; Wiedinmyer, C.; DeCarlo, P. F.; Ulbrich, I. M.; Wehrli, M. N.; Szidat, S.; Prevot, A. S. H.; Noda, J.; Wacker, L.; Volkamer, R.; Fortner, E.; Laskin, A.; Shutthanandan, V.; Zheng, J.; Zhang, R.; Paredes-Miranda, G.; Arnott, W. P.; Molina, L. T.; Sosa, G.; Querol, X.; Jimenez, J. L.

    2010-06-16

    periods or a correlation with fire counts, FLEXPART-predicted FIFs or fire tracers, indicating that it is dominated by urban and/or regional sources and not by the fires near the MCMA. A new 14C aerosol dataset is presented. Both this new and a previously published dataset of 14C analysis suggest a similar BBOA contribution as the AMS and chemical mass balance (CMB), resulting in 13% higher non-fossil carbon during the high vs. low regional fire periods. The new dataset has {approx}15% more fossil carbon on average than the previously published one, and possible reasons for this discrepancy are discussed. During the low regional fire period, 38% of organic carbon (OC) and 28% total carbon (TC) are from non-fossil sources, suggesting the importance of urban and regional non-fossil carbon sources other than the fires, such as food cooking and regional biogenic SOA. The ambient BBOA/CH3CN ratio is much higher in the afternoon when the wildfires are most intense than during the rest of the day. Also, there are large differences in the contributions of the different OA components to the surface concentrations vs. the integrated column amounts. Both facts may explain some apparent disagreements between BB impacts estimated from afternoon aircraft flights vs. those from 24-h ground measurements. We show that by properly accounting for the non-BB sources of K, all of the BB PM estimates from MILAGRO can be reconciled. Overall, the fires from the region near the MCMA are estimated to contribute 15-23% of the OA and 7-9% of the fine PM at T0 during MILAGRO, and 2-3% of the fine PM as an annual average. The 2006 MCMA emissions inventory contains a substantially lower impact of the forest fire emissions, although a fraction of these emissions occur just outside of the MCMA inventory area.

  8. Mexico city aerosol analysis during MILAGRO using high resolution aerosol mass spectrometry at the urban supersite (T0) - Part 2: Analysis of the biomass burning contribution and the non-fossil carbon fraction

    NASA Astrophysics Data System (ADS)

    Aiken, A. C.; de Foy, B.; Wiedinmyer, C.; Decarlo, P. F.; Ulbrich, I. M.; Wehrli, M. N.; Szidat, S.; Prevot, A. S. H.; Noda, J.; Wacker, L.; Volkamer, R.; Fortner, E.; Wang, J.; Laskin, A.; Shutthanandan, V.; Zheng, J.; Zhang, R.; Paredes-Miranda, G.; Arnott, W. P.; Molina, L. T.; Sosa, G.; Querol, X.; Jimenez, J. L.

    2010-06-01

    correlation with fire counts, FLEXPART-predicted FIFs or fire tracers, indicating that it is dominated by urban and/or regional sources and not by the fires near the MCMA. A new 14C aerosol dataset is presented. Both this new and a previously published dataset of 14C analysis suggest a similar BBOA contribution as the AMS and chemical mass balance (CMB), resulting in 13% higher non-fossil carbon during the high vs. low regional fire periods. The new dataset has ~15% more fossil carbon on average than the previously published one, and possible reasons for this discrepancy are discussed. During the low regional fire period, 38% of organic carbon (OC) and 28% total carbon (TC) are from non-fossil sources, suggesting the importance of urban and regional non-fossil carbon sources other than the fires, such as food cooking and regional biogenic SOA. The ambient BBOA/ΔCH3CN ratio is much higher in the afternoon when the wildfires are most intense than during the rest of the day. Also, there are large differences in the contributions of the different OA components to the surface concentrations vs. the integrated column amounts. Both facts may explain some apparent disagreements between BB impacts estimated from afternoon aircraft flights vs. those from 24-h ground measurements. We show that by properly accounting for the non-BB sources of K, all of the BB PM estimates from MILAGRO can be reconciled. Overall, the fires from the region near the MCMA are estimated to contribute 15-23% of the OA and 7-9% of the fine PM at T0 during MILAGRO, and 2-3% of the fine PM as an annual average. The 2006 MCMA emissions inventory contains a substantially lower impact of the forest fire emissions, although a fraction of these emissions occur just outside of the MCMA inventory area.

  9. Workplace aerosol mass concentration measurement using optical particle counters.

    PubMed

    Görner, Peter; Simon, Xavier; Bémer, Denis; Lidén, Göran

    2012-02-01

    Direct-reading aerosol measurement usually uses the optical properties of airborne particles to detect and measure particle concentration. In the case of occupational hygiene, mass concentration measurement is often required. Two aerosol monitoring methods are based on the principle of light scattering: optical particle counting (OPC) and photometry. The former analyses the light scattered by a single particle, the latter by a cloud of particles. Both methods need calibration to transform the quantity of scattered light detected into particle concentration. Photometers are simpler to use and can be directly calibrated to measure mass concentration. However, their response varies not only with aerosol concentration but also with particle size distribution, which frequently contributes to biased measurement. Optical particle counters directly measure the particle number concentration and particle size that allows assessment of the particle mass provided the particles are spherical and of known density. An integrating algorithm is used to calculate the mass concentration of any conventional health-related aerosol fraction. The concentrations calculated thus have been compared with simultaneous measurements by conventional gravimetric sampling to check the possibility of field OPC calibration with real workplace aerosols with a view to further monitoring particle mass concentration. Aerosol concentrations were measured in the food industry using the OPC GRIMM® 1.108 and the CIP 10-Inhalable and CIP 10-Respirable (ARELCO®) aerosol samplers while meat sausages were being brushed and coated with calcium carbonate. Previously, the original OPC inlet had been adapted to sample inhalable aerosol. A mixed aerosol of calcium carbonate and fungi spores was present in the workplace. The OPC particle-size distribution and an estimated average particle density of both aerosol components were used to calculate the mass concentration. The inhalable and respirable aerosol fractions

  10. Aerosol chemical mass closure during the EUROTRAC-2 AEROSOL Intercomparison 2000

    NASA Astrophysics Data System (ADS)

    Maenhaut, Willy; Schwarz, Jaroslav; Cafmeyer, Jan; Chi, Xuguang

    2002-04-01

    The field work for the AEROSOL Intercomparison 2000 took place from 4 to 14 April 2000 at Melpitz, Germany. One objective was to assess to which extent aerosol chemical mass closure could be obtained for the site. For this purpose, we operated four filter samplers in parallel (mostly using 12-h collections): two Gent PM10 stacked filter unit (SFU) samplers (one with coarse and fine Nuclepore polycarbonate filters, the other with a Gelman Teflo filter as fine filter) and two single filter holders (one with PM2.5 inlet, the other with PM10 inlet) with Whatman QM-A quartz fibre filters. All samples were analysed for the particulate mass (PM) by weighing; the samples from the first SFU were analysed for 42 elements by a combination of particle-induced X-ray emission spectroscopy and instrumental neutron activation analysis, those from the other SFU for major anions and cations by ion chromatography. All quartz filters were analysed for organic carbon and elemental carbon by a thermal-optical transmission technique. Aerosol chemical mass closure calculations were done for the separate fine (PM2) and coarse (2-10 μm) size fractions. As gravimetric PM data we used the averages from the parallel SFU collections. For reconstituting this PM, nine aerosol types (or components) were considered. Crustal matter, organic aerosol and nitrate were the major aerosol types in the coarse size fraction; the dominant aerosol types in the fine fraction were organic aerosol, nitrate and sulphate. The included components explained 116% and 86% of the gravimetric PM in the coarse and fine size fractions, respectively.

  11. Contribution of methane to aerosol carbon mass

    NASA Astrophysics Data System (ADS)

    Bianchi, F.; Barmet, P.; Stirnweis, L.; El Haddad, I.; Platt, S. M.; Saurer, M.; Lötscher, C.; Siegwolf, R.; Bigi, A.; Hoyle, C. R.; DeCarlo, P. F.; Slowik, J. G.; Prévôt, A. S. H.; Baltensperger, U.; Dommen, J.

    2016-09-01

    Small volatile organic compounds (VOC) such as methane (CH4) have long been considered non-relevant to aerosol formation due to the high volatility of their oxidation products. However, even low aerosol yields from CH4, the most abundant VOC in the atmosphere, would contribute significantly to the total particulate carbon budget. In this study, organic aerosol (OA) mass yields from CH4 oxidation were evaluated at the Paul Scherrer Institute (PSI) smog chamber in the presence of inorganic and organic seed aerosols. Using labeled 13C methane, we could detect its oxidation products in the aerosol phase, with yields up to 0.09

  12. ANALYSIS OF ATMOSPHERIC ORGANIC AEROSOLS BY MASS SPECTROSCOPY

    EPA Science Inventory

    High resolution mass spectroscopy has been found to be a useful means of characterizing the organic fraction of urban aerosols. Quantitative accuracy, however, was limited, particularly for compounds of low abundance. Some ambiguities were found in the assignment of origins of io...

  13. Mexico City Aerosol Analysis during MILAGRO using High Resolution Aerosol Mass Spectrometry at the Urban Supersite (T0). Part 2: Analysis of the Biomass Burning Contribution and the Modern Carbon Fraction

    SciTech Connect

    Aiken, Allison; de Foy, B.; Wiedinmyer, Christine; DeCarlo, Peter; Ulbrich, Ingrid M.; Wehrli, M. N.; Szidat, S.; Prevot, A. S. H.; Noda, J.; Wacker, L.; Volkamer, Rainer M.; Fortner, Edward; Wang, J. X.; Laskin, Alexander; Shutthanandan, V.; Zheng, J.; Zhang, Renyi; Paredes-Miranda, Guadalupe L.; Arnott, W. P.; Molina, Luis; Sosa, G.; Querol, X.; Jimenez, J. L.

    2010-06-16

    Submicron aerosol was analyzed during the MILAGRO field campaign in March 2006 at the T0 urban supersite in Mexico City with a High-Resolution Aerosol Mass Spectrometer (AMS) and complementary instrumentation. Positive Matrix Factorization (PMF) of high resolution AMS spectra identified a biomass burning OA (BBOA) component, which includes several large plumes that appear to be from forest fires within the region. Here, we show that the AMS BBOA concentration at T0 correlates with fire counts in the vicinity of Mexico City and that most of the BBOA variability is captured when the FLEXPART model is used for the dispersion of fire emissions as estimated from satellite fire counts. The resulting FLEXPART fire impact index correlates well with the observed BBOA, CH3CN, levoglucosan, and potassium, indicating that wildfires in the region surrounding Mexico City are the dominant source of BBOA at T0 during MILAGRO. The impact of distant BB sources such as the Yucatan is very small during this period. All fire tracers are correlated, with BBOA and levoglucosan showing little background, acetonitrile having a well-known tropospheric background of ~100-150 ppt, and PM2.5 potassium having a background of ~160 ng m-3 (two-thirds of its average concentration), which does not appear to be related to BB sources.

  14. Aerosols, cloud microphysics, and fractional cloudiness.

    PubMed

    Albrecht, B A

    1989-09-15

    Increases in aerosol concentrations over the oceans may increase the amount of low-level cloudiness through a reduction in drizzle-a process that regulates the liquid-water content and the energetics of shallow marine clouds. The resulting increase in the global albedo would be in addition to the increase due to enhancement in reflectivity associated with a decrease in droplet size and would contribute to a cooling of the earth's surface. PMID:17747885

  15. Determination of the biogenic secondary organic aerosol fraction in the boreal forest by NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Finessi, E.; Decesari, S.; Paglione, M.; Giulianelli, L.; Carbone, C.; Gilardoni, S.; Fuzzi, S.; Saarikoski, S.; Raatikainen, T.; Hillamo, R.; Allan, J.; Mentel, Th. F.; Tiitta, P.; Laaksonen, A.; Petäjä, T.; Kulmala, M.; Worsnop, D. R.; Facchini, M. C.

    2012-01-01

    The study investigates the sources of fine organic aerosol (OA) in the boreal forest, based on measurements including both filter sampling (PM1) and online methods and carried out during a one-month campaign held in Hyytiälä, Finland, in spring 2007. Two aerosol mass spectrometers (Q-AMS, ToF-AMS) were employed to measure on-line concentrations of major non-refractory aerosol species, while the water extracts of the filter samples were analyzed by nuclear magnetic resonance (NMR) spectroscopy for organic functional group characterization of the polar organic fraction of the aerosol. AMS and NMR spectra were processed separately by non-negative factorization algorithms, in order to apportion the main components underlying the submicrometer organic aerosol composition and depict them in terms of both mass fragmentation patterns and functional group compositions. The NMR results supported the AMS speciation of oxidized organic aerosol (OOA) into two main fractions, which could be generally labelled as more and less oxidized organics. The more oxidized component was characterized by a mass spectrum dominated by the m/z 44 peak, and in parallel by a NMR spectrum showing aromatic and aliphatic backbones highly substituted with oxygenated functional groups (carbonyls/carboxyls and hydroxyls). Such component, contributing on average 50% of the OA mass throughout the observing period, was associated with pollution outbreaks from the Central Europe. The less oxidized component was enhanced in concomitance with air masses originating from the North-to-West sector, in agreement with previous investigations conducted at this site. NMR factor analysis was able to separate two distinct components under the less oxidized fraction of OA. One of these NMR-factors was associated with the formation of terrestrial biogenic secondary organic aerosol (BSOA), based on the comparison with spectral profiles obtained from laboratory experiments of terpenes photo-oxidation. The second NMR

  16. Iron isotopic fractionation in industrial emissions and urban aerosols.

    PubMed

    Flament, Pascal; Mattielli, Nadine; Aimoz, Laure; Choël, Marie; Deboudt, Karine; de Jong, Jeroen; Rimetz-Planchon, Juliette; Weis, Dominique

    2008-12-01

    A study on tropospheric aerosols involving Fe particles with an industrial origin is tackled here. Aerosols were collected at the largest exhausts of a major European steel metallurgy plant and around its near urban environment. A combination of bulk and individual particle analysis performed by SEM-EDX provides the chemical composition of Fe-bearing aerosols emitted within the factory process (hematite, magnetite and agglomerates of these oxides with sylvite (KCl), calcite (CaCO(3)) and graphite carbon). Fe isotopic compositions of those emissions fall within the range (0.08 per thousandfractionation during steelworks processes is observed. At the industrial source, Fe is mainly present as oxide particles, to some extent in 3-4mum aggregates. In the close urban area, 5km away from the steel plant, individual particle analysis of collected aerosols presents, in addition to the industrial particle type, aluminosilicates and related natural particles (gypsum, quartz, calcite and reacted sea salt). The Fe isotopic composition (delta(56)Fe=0.14+/-0.11 per thousand) measured in the close urban environment of the steel metallurgy plant appears coherent with an external mixing of industrial and continental Fe-containing tropospheric aerosols, as evidenced by individual particle chemical analysis. Our isotopic data provide a first estimation of an anthropogenic source term as part of the study of photochemically promoted dissolution processes and related Fe fractionations in tropospheric aerosols. PMID:18851869

  17. Secondary Ion Mass Spectrometry of Environmental Aerosols

    SciTech Connect

    Gaspar, Daniel J.; Cliff, John B.

    2010-08-01

    Atmospheric particles influence many aspects of climate, air quality and human health. Understanding the composition, chemistry and behavior of atmospheric aerosols is a key remaining challenge in improving climate models. Furthermore, particles may be traced back to a particular source based on composition, stable isotope ratios, or the presence of particular surface chemistries. Finally, the characterization of atmospheric particles in the workplace plays an important role in understanding the potential for exposure and environmental and human health effects to engineered and natural nanoscale particles. Secondary ion mass spectrometry (SIMS) is a useful tool in determining any of several aspects of the structure, composition and chemistry of these particles. Often used in conjunction with other surface analysis and electron microscopy methods, SIMS has been used to determine or confirm reactions on and in particles, the presence of particular organic species on the surface of atmospheric aerosols and several other interesting and relevant findings. Various versions of SIMS instruments – dynamic SIMS, time of flight secondary ion mass spectrometry or TOF-SIMS, nanoSIMS – have been used to determine specific aspects of aerosol structure and chemistry. This article describes the strengths of each type of SIMS instrument in the characterization of aerosols, along with guidance on sample preparation, specific characterization specific to the particular information sought in the analysis. Examples and guidance are given for each type of SIMS analysis.

  18. 13C and 15N fractionation of CH4/N2 mixtures during photochemical aerosol formation: Relevance to Titan

    NASA Astrophysics Data System (ADS)

    Sebree, Joshua A.; Stern, Jennifer C.; Mandt, Kathleen E.; Domagal-Goldman, Shawn D.; Trainer, Melissa G.

    2016-05-01

    The ratios of the stable isotopes that comprise each chemical species in Titan's atmosphere provide critical information towards understanding the processes taking place within its modern and ancient atmosphere. Several stable isotope pairs, including 12C/13C and 14N/15N, have been measured in situ or probed spectroscopically by Cassini-borne instruments, space telescopes, or through ground-based observations. Current attempts to model the observed isotope ratios incorporate fractionation resulting from atmospheric diffusion, hydrodynamic escape, and primary photochemical processes. However, the effect of a potentially critical pathway for isotopic fractionation - organic aerosol formation and subsequent deposition onto the surface of Titan - has not been considered due to insufficient data regarding fractionation during aerosol formation. To better understand the nature of this process, we have conducted a laboratory study to measure the isotopic fractionation associated with the formation of Titan aerosol analogs, commonly referred to as 'tholins', via far-UV irradiation of several methane (CH4) and dinitrogen (N2) mixtures. Analysis of the δ13C and δ15N isotopic signatures of the photochemical aerosol products using an isotope ratio mass spectrometer (IRMS) show that fractionation direction and magnitude are dependent on the initial bulk composition of the gas mixture. In general, the aerosols showed enrichment in 13C and 14N, and the observed fractionation trends can provide insight into the chemical mechanisms controlling photochemical aerosol formation.

  19. DESIGN AND PERFORMANCE OF AN AEROSOL MASS DISTRIBUTION MONITOR

    EPA Science Inventory

    An aerosol mass monitor has been built to measure the masses of non-volatile aerosols in the range of 0.05 to 5 micrometers aerodynamic particle diameter. The instrument consists of a newly designed spiral duct aerosol centrifuge equipped with highly sensitive quartz sensors for ...

  20. Organic Aerosols in Rural and Remote Atmospheric Environments: Insights from Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Zhang, Q.; Jimenez, J.; Ulbrich, I.; Dunlea, E.; Decarlo, P.; Huffman, A.; Allan, J.; Coe, H.; Alfarra, R.; Canagaratna, M.; Onasch, T.; Jayne, J.; Worsnop, D.; Takami, A.; Miyoshi, T.; Shimono, A.; Hatakeyama, S.; Weimer, S.; Demerjian, K.; Drewnick, F.; Schneider, J.; Middlebrook, A.; Bahreini, R.; Cotrell, L.; Griffin, R.; Leaitch, R.; Li, S.; Hayden, K.; Rautiainen, J.

    2006-12-01

    Organic matter usually accounts for a large fraction of the fine particle mass in rural and remote atmospheres. However, little is known about the sources and properties of this material. Here we report findings on the characteristics and the major types of organic aerosols (OA) in urban downwind, high elevation, forested, and marine atmospheres based on analyses of more than 20 highly time resolved AMS datasets sampled from various locations in the mid-latitude Northern Hemisphere. Organic aerosol components are extracted from these datasets using a custom multiple component mass spectral analysis technique and the Positive Matrix Factorization (PMF) method. These components are evaluated according to their extracted mass spectra and correlations to aerosol species, such as sulfate, nitrate, and elemental carbon, and gas-phase tracer compounds, such as CO and NOx. We have identified a hydrocarbon-like organic aerosol (HOA) component similar in mass spectra to the hydrocarbon substances observed at urban locations. We have also identified several oxygenated OA (OOA) components that show different fragmentation patterns and oxygen to carbon ratios in their mass spectra. Two OOA components a highly oxygenated that has mass spectrum resembling that of fulvic acid (a model compound representative for highly processed/oxidized organics in the environment) and a less oxygenated OOA component, whose spectrum is dominated with ions that are mainly associated with carbonyls and alcohols, are very frequently observed at various rural/remote sites. The oxygenated OOA component is more prevalent at downwind sites influenced by urban transport and the less oxygenated shows correlation to biogenic chamber OA at some locations. Compared to the total OOA concentration, HOA is generally very small and accounts for < 10% of the total OA mass at rural/remote sites. The comparisons between the concentrations of HOA and primary OA (POA) that would be predicted according to inert

  1. Stable Carbon Fractionation In Size Segregated Aerosol Particles Produced By Controlled Biomass Burning

    NASA Astrophysics Data System (ADS)

    Masalaite, Agne; Garbaras, Andrius; Garbariene, Inga; Ceburnis, Darius; Martuzevicius, Dainius; Puida, Egidijus; Kvietkus, Kestutis; Remeikis, Vidmantas

    2014-05-01

    Biomass burning is the largest source of primary fine fraction carbonaceous particles and the second largest source of trace gases in the global atmosphere with a strong effect not only on the regional scale but also in areas distant from the source . Many studies have often assumed no significant carbon isotope fractionation occurring between black carbon and the original vegetation during combustion. However, other studies suggested that stable carbon isotope ratios of char or BC may not reliably reflect carbon isotopic signatures of the source vegetation. Overall, the apparently conflicting results throughout the literature regarding the observed fractionation suggest that combustion conditions may be responsible for the observed effects. The purpose of the present study was to gather more quantitative information on carbonaceous aerosols produced in controlled biomass burning, thereby having a potential impact on interpreting ambient atmospheric observations. Seven different biomass fuel types were burned under controlled conditions to determine the effect of the biomass type on the emitted particulate matter mass and stable carbon isotope composition of bulk and size segregated particles. Size segregated aerosol particles were collected using the total suspended particle (TSP) sampler and a micro-orifice uniform deposit impactor (MOUDI). The results demonstrated that particle emissions were dominated by the submicron particles in all biomass types. However, significant differences in emissions of submicron particles and their dominant sizes were found between different biomass fuels. The largest negative fractionation was obtained for the wood pellet fuel type while the largest positive isotopic fractionation was observed during the buckwheat shells combustion. The carbon isotope composition of MOUDI samples compared very well with isotope composition of TSP samples indicating consistency of the results. The measurements of the stable carbon isotope ratio in

  2. USE OF ANALYTICALLY DEFINED ESTIMATES OF AEROSOL RESPIRABLE FRACTION TO PREDICT LUNG DEPOSITION PATTERNS

    EPA Science Inventory

    Analytical estimates of the respirable fractions of inhaled pharmaceutical aerosols are obtained by inertial sampling techniques. The respirable fraction may be defined as the prescribed fraction of the particle size distribution less than a designated diameter. The diameter belo...

  3. Characterization of aerosol composition, concentrations, and sources at Baengnyeong Island, Korea using an aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Lee, Taehyoung; Choi, Jinsoo; Lee, Gangwoong; Ahn, Junyoung; Park, Jin Soo; Atwood, Samuel A.; Schurman, Misha; Choi, Yongjoo; Chung, Yoomi; Collett, Jeffrey L.

    2015-11-01

    To improve understanding of the sources and chemical properties of particulate pollutants on the western side of the Korean Peninsula, an Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS) measured non-refractory fine (PM1) particles from May to November, 2011 at Baengnyeong Island, South Korea. Organic matter and sulfate were generally the most abundant species and exhibited maximum concentrations of 36 μg/m3 and 39 μg/m3, respectively. Nitrate concentrations peaked at 32 μg/m3 but were typically much lower than sulfate and organic matter concentrations. May, September, October, and November featured the highest monthly average concentrations, with lower concentrations typically observed from June through August. Potential source contribution function (PSCF) analysis and individual case studies revealed that transport from eastern China, an area with high SO2 emissions, was associated with high particulate sulfate concentrations at the measurement site. Observed sulfate aerosol sometimes was fully neutralized by ammonium but often was acidic; the average ammonium to sulfate molar ratio was 1.49. Measured species size distributions revealed a range of sulfate particle size distributions with modes between 100 and 600 nm. Organic aerosol source regions were widespread, including contributions from eastern China and South Korea. Positive matrix factorization (PMF) analysis indicated three "factors," or types of organic aerosol, comprising one primary, hydrocarbon-like organic aerosol (HOA) and two oxidized organic aerosol (OOA) components, including a more oxidized (MO-OOA) and a less oxidized (LO-OOA) oxidized organic aerosol. On average, HOA and OOA contributed 21% and 79% of the organic mass (OM), respectively, with the MO-OOA fraction nearly three times as abundant as the LO-OOA fraction. Biomass burning contributions to observed OM were low during the late spring/early summer agricultural burning season in eastern China, since

  4. Characterization and source apportionment of organic aerosol using offline aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Daellenbach, K. R.; Bozzetti, C.; Křepelová, A.; Canonaco, F.; Wolf, R.; Zotter, P.; Fermo, P.; Crippa, M.; Slowik, J. G.; Sosedova, Y.; Zhang, Y.; Huang, R.-J.; Poulain, L.; Szidat, S.; Baltensperger, U.; Prévôt, A. S. H.; El Haddad, I.

    2015-08-01

    Field deployments of the Aerodyne Aerosol Mass Spectrometer (AMS) have significantly advanced real-time measurements and source apportionment of non-refractory particulate matter. However, the cost and complex maintenance requirements of the AMS make impractical its deployment at sufficient sites to determine regional characteristics. Furthermore, the negligible transmission efficiency of the AMS inlet for supermicron particles significantly limits the characterization of their chemical nature and contributing sources. In this study, we utilize the AMS to characterize the water-soluble organic fingerprint of ambient particles collected onto conventional quartz filters, which are routinely sampled at many air quality sites. The method was applied to 256 particulate matter (PM) filter samples (PM1, PM2.5, PM10) collected at 16 urban and rural sites during summer and winter. We show that the results obtained by the present technique compare well with those from co-located online measurements, e.g. AMS or Aerosol Chemical Speciation Monitor (ACSM). The bulk recoveries of organic aerosol (60-91 %) achieved using this technique, together with low detection limits (0.8 μg of organic aerosol on the analyzed filter fraction) allow its application to environmental samples. We will discuss the recovery variability of individual hydrocarbon, oxygen containing and other ions. The performance of such data in source apportionment is assessed in comparison to ACSM data. Recoveries of organic components related to different sources as traffic, wood burning and secondary organic aerosol are presented. This technique, while subjected to the limitations inherent to filter-based measurements (e.g. filter artifacts and limited time resolution) may be used to enhance the AMS capabilities in measuring size-fractionated, spatially-resolved long-term datasets.

  5. Characterization and source apportionment of organic aerosol using offline aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Daellenbach, K. R.; Bozzetti, C.; Křepelová, A.; Canonaco, F.; Wolf, R.; Zotter, P.; Fermo, P.; Crippa, M.; Slowik, J. G.; Sosedova, Y.; Zhang, Y.; Huang, R.-J.; Poulain, L.; Szidat, S.; Baltensperger, U.; El Haddad, I.; Prévôt, A. S. H.

    2016-01-01

    Field deployments of the Aerodyne Aerosol Mass Spectrometer (AMS) have significantly advanced real-time measurements and source apportionment of non-refractory particulate matter. However, the cost and complex maintenance requirements of the AMS make its deployment at sufficient sites to determine regional characteristics impractical. Furthermore, the negligible transmission efficiency of the AMS inlet for supermicron particles significantly limits the characterization of their chemical nature and contributing sources. In this study, we utilize the AMS to characterize the water-soluble organic fingerprint of ambient particles collected onto conventional quartz filters, which are routinely sampled at many air quality sites. The method was applied to 256 particulate matter (PM) filter samples (PM1, PM2.5, and PM10, i.e., PM with aerodynamic diameters smaller than 1, 2.5, and 10 µm, respectively), collected at 16 urban and rural sites during summer and winter. We show that the results obtained by the present technique compare well with those from co-located online measurements, e.g., AMS or Aerosol Chemical Speciation Monitor (ACSM). The bulk recoveries of organic aerosol (60-91 %) achieved using this technique, together with low detection limits (0.8 µg of organic aerosol on the analyzed filter fraction) allow its application to environmental samples. We will discuss the recovery variability of individual hydrocarbon ions, ions containing oxygen, and other ions. The performance of such data in source apportionment is assessed in comparison to ACSM data. Recoveries of organic components related to different sources as traffic, wood burning, and secondary organic aerosol are presented. This technique, while subjected to the limitations inherent to filter-based measurements (e.g., filter artifacts and limited time resolution) may be used to enhance the AMS capabilities in measuring size-fractionated, spatially resolved long-term data sets.

  6. Factor analysis of combined organic and inorganic aerosol mass spectra from high resolution aerosol mass spectrometer measurements

    NASA Astrophysics Data System (ADS)

    Sun, Y. L.; Zhang, Q.; Schwab, J. J.; Yang, T.; Ng, N. L.; Demerjian, K. L.

    2012-09-01

    Positive matrix factorization (PMF) was applied to the merged high resolution mass spectra of organic and inorganic aerosols from aerosol mass spectrometer (AMS) measurements to investigate the sources and evolution processes of submicron aerosols in New York City in summer 2009. This new approach is able to study the distribution of organic and inorganic species in different types of aerosols, the acidity of organic aerosol (OA) factors, and the fragment ion patterns related to photochemical processing. In this study, PMF analysis of the unified AMS spectral matrix resolved 8 factors. The hydrocarbon-like OA (HOA) and cooking OA (COA) factors contain negligible amounts of inorganic species. The two factors that are primarily ammonium sulfate (SO4-OA) and ammonium nitrate (NO3-OA), respectively, are overall neutralized. Among all OA factors the organic fraction of SO4-OA shows the highest degree of oxidation (O/C = 0.69). Two semi-volatile oxygenated OA (OOA) factors, i.e., a less oxidized (LO-OOA) and a more oxidized (MO-OOA), were also identified. MO-OOA represents local photochemical products with a diurnal profile exhibiting a pronounced noon peak, consistent with those of formaldehyde (HCHO) and Ox(= O3 + NO2). The NO+/NO2+ ion ratio in MO-OOA is much higher than that in NO3-OA and in pure ammonium nitrate, indicating the formation of organic nitrates. The nitrogen-enriched OA (NOA) factor contains ~25% of acidic inorganic salts, suggesting the formation of secondary OA via acid-base reactions of amines. The size distributions of OA factors derived from the size-resolved mass spectra show distinct diurnal evolving behaviors but overall a progressing evolution from smaller to larger particle mode as the oxidation degree of OA increases. Our results demonstrate that PMF analysis of the unified aerosol mass spectral matrix which contains both inorganic and organic aerosol signals may enable the deconvolution of more OA factors and gain more insights into the

  7. Nitrogen isotopic fractionation during plasma synthesis of Titan's aerosols analogues

    NASA Astrophysics Data System (ADS)

    Kuga, M.; Carrasco, N.; Marty, B.; Marrocchi, Y.; Bernard, S.; Rigaudier, T.

    2013-12-01

    The Cassini-Huygens mission recently provided measurements of the abundance of nitrogen isotopes in Titan's atmosphere. The 14N/15N ratio in the two most abundant N-bearing molecules in Titan's atmosphere was found to be 183×5 for N2 [1] and 56×8 for HCN [2]. Those two molecules are greatly enriched in the heavier isotope 15N compared to our terrestrial atmosphere and Titan's HCN is about three times richer in 15N than its potential photochemical precursor N2. This implies an important fractionation process in the HCN production chain, which is tentatively attributed to an isotopic selectivity of the photodissociation of N2 in Titan's ionosphere [3-4]. The organic aerosols, forming the Titan's orange characteristic haze layers, also contain large amounts of nitrogen [5], and thus represent a third important nitrogen reservoir in Titan's atmosphere. These organic aerosols are presumably produced in the upper atmosphere by chemical reactions between N2 and CH4 induced by solar radiation and electron bombardment from Saturn's magnetosphere. As HCN is a possible precursor for aerosol polymerization [6-7], the 15N enrichment observed in HCN may be linked to the polymerization process. Unfortunately, no data exists on the isotopic nitrogen abundance in Titan's aerosols, and this question remains open. To address this issue, laboratory aerosols analogues have been produced in a N2-CH4 plasma and their nitrogen isotopic composition have been investigated. In this study, the experimental aerosols, called " tholins ", have been synthetized in the PAMPRE reactor (LATMOS, France). This setup is dedicated to simulate chemical processes occurring in Titan's atmosphere and consists in an RF plasma discharge initiated in a N2-CH4 gas mixture at room temperature [8-9]. For our purpose, tholins were produced at different initial CH4 percentages (1, 2, 5, 10%), representative of the variation of the CH4 concentration in Titan's atmosphere. 15N/14N ratio of the N2 gas used in the

  8. Characterization of ice-nucleating bacteria using on-line electron impact ionization aerosol mass spectrometry.

    PubMed

    Wolf, R; Slowik, J G; Schaupp, C; Amato, P; Saathoff, H; Möhler, O; Prévôt, A S H; Baltensperger, U

    2015-04-01

    The mass spectral signatures of airborne bacteria were measured and analyzed in cloud simulation experiments at the AIDA (Aerosol Interaction and Dynamics in the Atmosphere) facility. Suspensions of cultured cells in pure water were sprayed into the aerosol and cloud chambers forming an aerosol which consisted of intact cells, cell fragments and residual particles from the agar medium in which the bacteria were cultured. The aerosol particles were analyzed with a high-resolution time-of-flight aerosol mass spectrometer equipped with a newly developed PM2.5 aerodynamic lens. Positive matrix factorization (PMF) using the multilinear engine (ME-2) source apportionment was applied to deconvolve the bacteria and agar mass spectral signatures. The bacteria mass fraction contributed between 75 and 95% depending on the aerosol generation, with the remaining mass attributed to agar. We present mass spectra of Pseudomonas syringae and Pseudomonas fluorescens bacteria typical for ice-nucleation active bacteria in the atmosphere to facilitate the distinction of airborne bacteria from other constituents in ambient aerosol, e.g. by PMF/ME-2 source apportionment analyses. Nitrogen-containing ions were the most salient feature of the bacteria mass spectra, and a combination of C4 H8 N(+) (m/z 70) and C5 H12 N(+) (m/z 86) may be used as marker ions. PMID:26149110

  9. Influence of measurement uncertainties on fractional solubility of iron in mineral aerosols over the oceans

    NASA Astrophysics Data System (ADS)

    Meskhidze, Nicholas; Johnson, Matthew S.; Hurley, David; Dawson, Kyle

    2016-09-01

    The atmospheric supply of mineral dust iron (Fe) plays a crucial role in the Earth's biogeochemical cycle and is of specific importance as a micronutrient in the marine environment. Observations show several orders of magnitude variability in the fractional solubility of Fe in mineral dust aerosols, making it hard to assess the role of mineral dust in the global ocean biogeochemical Fe cycle. In this study we compare the operational solubility of mineral dust aerosol Fe associated with the flow-through leaching protocol to the results of the global 3-D chemical transport model GEOS-Chem. According to the protocol, aerosol Fe is defined as soluble by first deionized water leaching of mineral dust through a 0.45 μm pore size membrane followed by acidification and storage of the leachate over a long period of time prior to analysis. To estimate the uncertainty in soluble Fe results introduced by the flow-through leaching protocol, we prescribe an average 50% (range of 30-70%) fractional solubility to sub-0.45 μm sized mineral dust particles that may inadvertently pass the filter and end up in the acidified (at pH ∼ 1.7) leachate for a couple of month period. In the model, the fractional solubility of Fe is either explicitly calculated using a complex mineral aerosol Fe dissolution equations, or prescribed to be 1% and 4% often used by global ocean biogeochemical Fe cycle models to reproduce the broad characteristics of the presently observed ocean dissolved iron distribution. Calculations show that the fractional solubility of Fe derived through the flow-through leaching is higher compared to the model results. The largest differences (∼40%) are predicted to occur farther away from the dust source regions, over the areas where sub-0.45 μm sized mineral dust particles contribute a larger fraction of the total mineral dust mass. This study suggests that different methods used in soluble Fe measurements and inconsistences in the operational definition of

  10. Carbon and nitrogen isotope fractionation during possible organic aerosol formation in Titan and the early Earth

    NASA Astrophysics Data System (ADS)

    Imanaka, H.

    2012-12-01

    Abiotic formation of complex organic macromolecule aerosols is important not only for the potential for prebiotic chemical evolution, but also in the global elemental cycle. The direct clues of the habitable environment and biosphere on the early Earth are mostly obtained from geological records, such as isotope signatures and biomarkers in the ancient organic sediments. The recent Cassini-Huygens mission revealed the generation of complex organic aerosols in Titan's upper atmosphere, and similar processes could have lead to the formation of organic aerosols in the early Earth atmosphere. Understanding the formation reaction network and accompanying isotope fractionation processes of the organic aerosols is necessary to constrain the active organic environment on the early Earth from the available geological evidence. We have investigated the abiotic formation of organic aerosols in simulated atmospheres of Titan and the early, with particular focus on carbon and nitrogen isotope fractionation. Laboratory aerosol analogues, termed tholins, are generated with cold plasma irradiation of reduced gas mixtures, such as N2/CH4 and N2/H2/CO. Stable isotopic ratios of 15N/14N and 13C/12C for the generated tholins are measured with an elemental analysis-isotope ratio mass spectrometer (EA-IR-MS). Our preliminary data for tholins generated from an equivalent N2/CH4 (=90/10) gas mixture at various pressures suggests the 15N isotopic fractionation up to δ15N = -20~25 permil during tholin formation, while 13C isotopic fractionation seems almost negligible. This negative δ15N is even lighter than those observed in kerogens in the Archean sediments (Beaumont and Robert, 1999; Pinti et al., 2001), and the organic haze could have contributed to the source of 15N-depleted kerogens. Furthermore, the δ15N vary with deposition pressure. Previous works demonstrated that the resulted two types of tholin are very different in chemical structure and optical properties (Imanaka et al

  11. Determination of the biogenic secondary organic aerosol fraction in the boreal forest by AMS and NMR measurements

    NASA Astrophysics Data System (ADS)

    Finessi, E.; Decesari, S.; Paglione, M.; Giulianelli, L.; Carbone, C.; Gilardoni, S.; Fuzzi, S.; Saarikoski, S.; Raatikainen, T.; Hillamo, R.; Allan, J.; Mentel, Th. F.; Tiitta, P.; Laaksonen, A.; Petäjä, T.; Kulmala, M.; Worsnop, D. R.; Facchini, M. C.

    2011-08-01

    The study investigates the sources of fine organic aerosol (OA) in the boreal forest, based on measurements including both filter sampling (PM1) and online methods and carried out during a one-month campaign held in Hyytiälä, Finland, in spring 2007. Two aerosol mass spectrometers (Q-AMS, ToF-AMS) were employed to measure on-line air mass concentrations of major non-refractory aerosol species, while the water extracts of the filter samples were analyzed by nuclear magnetic resonance (NMR) spectroscopy for organic functional group characterization of the polar organic fraction of the aerosol. AMS and NMR spectra were processed separately by non-negative factorization algorithms, in order to apportion the main components underlying the submicrometer organic aerosol composition and depict them in terms of both mass fragmentation patterns and functional group compositions. The NMR results supported the AMS speciation of oxidized organic aerosol (OOA) into two main fractions, which could be generally labelled as more and less oxidized organics. The more oxidized component was characterized by a mass spectrum dominated by the m/z 44 peak, and in parallel by a NMR spectrum showing aromatic and aliphatic backbones highly substituted with oxygenated functional groups (carbonyls/carboxyls and hydroxyls). Such component, contributing on average 50 % of the OA mass throughout the observing period, was associated with pollution outbreaks from the Central Europe. The less oxidized component showed features consistent with less oxygenated aerosols and was enhanced in concomitance with air masses originating from the North-to-West sector, in agreement with previous investigations conducted at this site. NMR factor analysis was able to separate two distinct components under the less oxidized fraction of OA. One of these NMR-factors was associated to the formation of terrestrial biogenic secondary organic aerosol (BSOA), based on the comparison with spectral profiles obtained from

  12. Contributions of Acid-Catalysed Processes to Secondary Organic Aerosol Mass - A Modelling pproach

    NASA Astrophysics Data System (ADS)

    Ervens, B.; Feingold, G.; Kreidenweis, S. M.

    2005-12-01

    A significant fraction of secondary organic aerosol (SOA) mass is formed by chemical and/or physical processes. However, the amount of organic material found in ambient organic aerosols cannot be explained with current models. Recently, several laboratory studies have been published which suggest that also acid-catalyzed processes that occur either in particles or at their surfaces (heterogeneous) might contribute significantly to mass formation. However, to date there is no general conclusion about the efficiency of such processes due to the great diversity of species and experimental conditions. We present a compilation of literature data (thermodynamic and kinetic) of these processes. The aerosol yields of (i) additional species which are thought previously not contribute to SOA formation (e.g. isoprene, aliphatic aldehydes) and (ii) species which form apparently higher SOA masses on acidic seed aerosols are reported and compared to input data of previous SOA models. Available kinetic data clearly exclude aldol condensation as a significant process for SOA formation on a time scale of typical aerosol life times. Using aerosol size distributions and gas phase concentrations measured during NEAQS2002 as model input data, we show that (even under assumption of equilibrium conditions) these additional processes only contribute a minor fraction to the organic aerosol mass.

  13. Chemical Analysis of Fractionated Halogens in Atmospheric Aerosols Collected in Okinawa, Japan

    NASA Astrophysics Data System (ADS)

    Tsuhako, A.; Miyagi, Y.; Somada, Y.; Azechi, S.; Handa, D.; Oshiro, Y.; Murayama, H.; Arakaki, T.

    2013-12-01

    Halogens (Cl, Br and I) play important roles in the atmosphere, e.g. ozone depletion by Br during spring in Polar Regions. Sources of halogens in atmospheric aerosols are mainly from ocean. But, for example, when we analyzed Br- with ion chromatography, its concentrations were almost always below the detection limit, which is also much lower than the estimated concentrations from sodium ion concentrations. We hypothesized that portions of halogens are escaped to the atmosphere, similar to chlorine loss, changed their chemical forms to such as BrO3- and IO3-, and/or even formed precipitates. There was few reported data so far about fractionated halogen concentrations in atmospheric aerosols. Thus, purpose of this study was to determine halogen concentrations in different fractions; free ion, water-soluble chemically transformed ions and precipitates using the authentic aerosols. Moreover, we analyzed seasonal variation for each fraction. Atmospheric aerosol samples were collected at Cape Hedo Atmosphere and Aerosol Monitoring Station (CHAAMS) of Okinawa, Japan during January 2010 and August 2013. A high volume air sampler was used for collecting total particulate matters on quartz filters on a weekly basis. Ultrapure water was used to extract water-soluble factions of halogens. The extracted solutions were filtered with the membrane filter and used for chemical analysis with ion chromatography and ICP-MS. Moreover, the total halogens in aerosols were obtained after digesting aerosols with tetramethylammonium hydroxide (TMAH) using the microwave and analysis with ICP-MS. For Cl, water-soluble Cl- accounted for about 70% of the estimates with Na content. No other forms of water-soluble Cl were found. About 30% of Cl was assumed volatilized to the gas-phase. For Br, water-soluble Br accounted for about 43% of the estimates with Na content, and within the 43%, about 10% of Br was not in the form of Br-. About 46% of Br was assumed volatilized to the gas-phase. For I

  14. Source and composition of size fractionated aerosols collected in the Central Valley

    NASA Astrophysics Data System (ADS)

    Allen, G.; Kelly, P. B.; Buchholz, B. A.; Clifford, A.

    2013-12-01

    The Central Valley in California has historically had high levels of atmospheric particulate matter (PM), resulting in significant adverse health effects. The three sources of atmospheric PM in the Central Valley are vehicle exhaust emissions, agricultural activity and residential wood burning. Ambient PM was collected during the winter of 2011 and 2012 in Davis, CA using a DRUM impact analyzer to determine the contributions of the various sources to the size fractionated aerosols. Laser desorption ionization time-of-flight mass spectrometry (LDI-TOF MS) and radiocarbon accelerator mass spectrometry (AMS) were performed on size fractionated atmospheric PM. The results show that as particle size decreases the amount of organic carbon increases. In the smallest size fraction (0.09 - 1.2 μm) the organic carbon encompasses approximately 70% of the LDI-TOF signal intensity. A comparison of the size fraction PM LDI-TOF spectra showed that there was a significant difference in the chemical composition with particle size. Three distinct chemical composition modes were observed in the LDI-TOF analysis: 0.09 to 0.34 μm, 0.34 to 0.56 μm and >0.56 μm. The particles <0.34 μm were found to be statistically different than those >0.5 μm. The chemical difference in the PM is driven by the large amount of secondary organic aerosol. Dicarboxylic acids, aromatic acids and nitrated aromatics were predominately found in particles <0.34 μm. The effect on human health of these compounds needs to be further explored. The difference in the chemical composition between the respirable and larger PM needs to be considered when associating health effects with PM exposure. The radiocarbon AMS analysis showed that the size fractionated total carbonaceous particulate matter was mainly biogenic in origin, having an average fraction modern (F14C) = 0.753 × 0.006. The F14C from both sample collections were similar and there wasn't a significant change in fraction modern as particle size

  15. Characterization of aerosol composition and sources in the greater Atlanta area by aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Ng, N. L.; Xu, L.; Suresh, S.; Weber, R. J. J.; Baumann, K.; Edgerton, E. S.

    2014-12-01

    An important and uncertain aspect of biogenic secondary organic aerosol (SOA) formation is that it is often associated with anthropogenic pollution tracers. Prior studies in Atlanta suggested that 70-80% of the carbon in water-soluble organic carbon (WSOC) is modern, yet it is well-correlated with the anthropogenic CO. In this study, we deployed a High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and an Aerosol Chemical Speciation Monitor (ACSM) at multiple sites in different seasons (May 2012-February 2013) to characterize the sources and chemical composition of aerosols in the greater Atlanta area. This area in the SE US is ideal to investigate anthropogenic-biogenic interactions due to high natural and anthropogenic emissions. These extensive field studies are part of the Southeastern Center for Air Pollution and Epidemiology study (SCAPE). The HR-ToF-AMS is deployed at four sites (~ 3 weeks each) in rotation: Jefferson Street (urban), Yorkville (rural), roadside site (near Highway 75/85), and Georgia Tech site (campus), with the urban and rural sites being part of the SEARCH network. We obtained seven HR-ToF-AMS datasets in total. During the entire measurement period, the ACSM is stationary at the GIT site and samples continuously. We perform positive matrix factorization (PMF) analysis on the HR-ToF-AMS and ACSM data to deconvolve the OA into different components. While the diurnal cycle of the total OA is flat as what have been previously observed, the OA factors resolved by PMF analysis show distinctively different diurnal trends. We find that the "more-oxidized oxygenated OA" (MO-OOA) constitutes a major fraction of OA at all sites. In summer, OA is dominated by SOA, e.g., isoprene-OA and OOA with different degrees of oxidation. In contrary, biomass burning OA is more prominent in winter data. By comparing HR-ToF-AMS and ACSM data during the same sampling periods, we find that the aerosol time series are highly correlated, indicating the

  16. Oxygen Isotope Anomaly in the Carbonate Fractions of Aerosols and its Potential to Assess Urban Pollution

    NASA Astrophysics Data System (ADS)

    Shaheen, R.; Abramian, A.; Dominguez, G.; Jackson, T.; Thiemens, M. H.

    2008-12-01

    Mineral dust is emitted into the atmosphere from arid regions in Asia yearly, accounting for ~36% of global aerosol emissions, 5900 Tg yr-1 [IPCC 2007]. Increasing anthropogenic emissions and persistent dust emissions not only have reduced the air quality in Asia itself, but are also affecting the pollutant deposition into the Pacific Ocean and air quality in downwind areas. The carbonate component of mineral dust (calcite (CaCO3) and dolomite (CaMg(CO3)2) is particularly reactive and can comprise as much as 30% of the total mineral dust aerosol, depending on the source region [Claquin et al., 1999]. Carbonate can affect atmospheric chemical processes and aerosol characteristics because the acid neutralizing capacity of this species facilitates the heterogeneous conversion of sulphate and nitrate. Understanding heterogeneous reactions occurring on the surface of aerosol particles will lead to a better understanding of the fate and transport of molecules in the troposphere as well as to resolve their role in air quality and pollution. The primary goal of this work is to develop an isotope methodology for carbonates that can be used as a chemical marker for the origin of polluted air plumes and chemical transformation during the long range transport of air masses. We will discuss the carbon and oxygen isotope composition of the CO2 released from the fine (< 1 μm) and coarse (> 1 μm) particles collected at two different sites [Mt. Soledad (800 ft) and Scripps Pier, La Jolla, California] and its possible utility as a tracer to identify the long-range transport of aerosol from local pollution events. The degree of urban influence of sampled air parcels at each site was quantified through back-trajectory analysis of NOAA HYSPLIT output data. Interestingly, the isotopes of oxygen did not follow standard mass dependent relationship (δ17O ~ 0.52 δ18O) rather have excess 17O (Δ17O = δ17O- 0.52δ18O) ranging from 0.9 to 3.9 per mil. A highly significant correlation (r2

  17. Aerosol chemical components in Alaska air masses: 1. Aged pollution

    NASA Astrophysics Data System (ADS)

    Shaw, Glenn E.

    1991-12-01

    A 4-year Alaska chemical data set of aerosols or "dust" in the air clearly reveals a mixture of distinct aerosol components with different and interesting chemical composition, one or two being ascribed to pollution imported to Alaska by winds all the way from other continents. Of particular note is a strong chemical contrast between what we imagine to be highly scavenged, orographically lifted, northern Pacific air (Pacific marine air mass) and stagnant Arctic air (polar air mass), the latter containing seasonal average concentrations of between 2-4 times the concentration of the former, at least for pollution markers noncrustal vanadium, noncrustal manganese, arsenic, selenium, bromine, and antimony. The findings concur our old discovery that Arctic air is persistently polluted (Arctic haze), but Pacific air is relatively clean, in spite of the fact that Alaska is downwind of major pollution sources in the Orient. This is remarkable. In this the first of a two-part paper, we concentrate on the pollution component found primarily during incursion of Arctic polar air. Two major occurrences of visual haze with optical depths of approximately 0.2 and elevated aerosol concentration lasting about a month (spring 1985 and 1986) were affiliated with strong incoming transport of polar air, temperatures ranging from 10° to 20°C below normal (polar air) and air trajectory hindcasts leading back to industrial pollution sources in Eurasia. These long-range transport pollution events brought metal-rich aerosol of removal-resistant submicron particles. The size, chemistry, and meteorology all strongly suggest the presence of a well-aged (10-100 day) polluted air mass. An important implication is that in spring a large fraction of the Arctic polar air mass becomes charged with by-products of industrial pollution. In this multiyear chemical data set one finds a notable summer-winter contrast, changing by factors of 2 to 4 for pollution markers As, Se, Sb, and noncrustal

  18. A two-sided fractional conservation of mass equation

    NASA Astrophysics Data System (ADS)

    Olsen, Jeffrey S.; Mortensen, Jeff; Telyakovskiy, Aleksey S.

    2016-05-01

    A two-sided fractional conservation of mass equation is derived by using left and right fractional Mean Value Theorems. This equation extends the one-sided fractional conservation of mass equation of Wheatcraft and Meerschaert. Also, a two-sided fractional advection-dispersion equation is derived. The derivations are based on Caputo fractional derivatives.

  19. Mass Fractionation Laws, Mass-Independent Effects, and Isotopic Anomalies

    NASA Astrophysics Data System (ADS)

    Dauphas, Nicolas; Schauble, Edwin A.

    2016-06-01

    Isotopic variations usually follow mass-dependent fractionation, meaning that the relative variations in isotopic ratios scale with the difference in mass of the isotopes involved (e.g., δ17O ≈ 0.5×δ18O). In detail, however, the mass dependence of isotopic variations is not always the same, and different natural processes can define distinct slopes in three-isotope diagrams. These variations are subtle, but improvements in analytical capabilities now allow precise measurement of these effects and make it possible to draw inferences about the natural processes that caused them (e.g., reaction kinetics versus equilibrium isotope exchange). Some elements, in some sample types, do not conform to the regularities of mass-dependent fractionation. Oxygen and sulfur display a rich phenomenology of mass-independent fractionation, documented in the laboratory, in the rock record, and in the modern atmosphere. Oxygen in meteorites shows isotopic variations that follow a slope-one line (δ17O ≈ δ18O) whose origin may be associated with CO photodissociation. Sulfur mass-independent fractionation in ancient sediments provides the tightest constraint on the oxygen partial pressure in the Archean and the timing of Earth's surface oxygenation. Heavier elements also show departures from mass fractionation that can be ascribed to exotic effects associated with chemical reactions such as magnetic effects (e.g., Hg) or the nuclear field shift effect (e.g., U or Tl). Some isotopic variations in meteorites and their constituents cannot be related to the terrestrial composition by any known process, including radiogenic, nucleogenic, and cosmogenic effects. Those variations have a nucleosynthetic origin, reflecting the fact that the products of stellar nucleosynthesis were not fully homogenized when the Solar System formed. Those anomalies are found at all scales, from nanometer-sized presolar grains to bulk terrestrial planets. They can be used to learn about stellar

  20. Some Technical Aspects of a CALIOP and MODIS Data Analysis that Examines Near-Cloud Aerosol Properties as a Function of Cloud Fraction

    NASA Technical Reports Server (NTRS)

    Varnai, Tamas; Yang, Weidong; Marshak, Alexander

    2016-01-01

    CALIOP shows stronger near-cloud changes in aerosol properties at higher cloud fractions. Cloud fraction variations explain a third of near-cloud changes in overall aerosol statistics. Cloud fraction and aerosol particle size distribution have a complex relationship.

  1. Comparison of particle lung doses from the fine and coarse fractions of urban PM-10 aerosols.

    PubMed

    Venkataraman, C; Kao, A S

    1999-02-01

    The U.S. Environmental Protection Agency (EPA) recently revised the national ambient air quality standards to include a new PM-2.5 particulate standard. We examine the contributions of fine (PM-2.5) and coarse (PM-2.5 to -10) fraction of typical urban aerosols to particle doses in different lung airways resulting from 24-h exposure to the standard concentration of 150 microg m-3. The aerosol is assumed to have a bimodal lognormal mass distribution with mass median diameters of 0.2 and 5 microm, and geometric standard deviation of 1.7 and 57% of the mass in the fine (PM-2.5) mode. The daily mass dose from exposure to 150 microg m-3 of PM-10 in the nasopharyngeal (NPL) region is 20-51 microg day-1 (1.5% of inhaled fines) and 377-687 microg day-1 (30% of inhaled coarse), respectively, of fine and coarse mass filtered in the nose. Similar daily mass doses from fine and coarse fractions, respectively, to the tracheobronchial (TBL) region are 28-38 (1.5%) and 40-52 (4%) microg day-1 and to the pulmonary (PUL) region are 18-194 (6%) and 32-55 microg day-1 (2%). The daily number dose in the NPL region is 5-15 x 10(8) (0.06% of inhaled fines) and 5-10 x 10(6) day-1 (13% of inhaled coarse) respectively, of fine and coarse particles. Similar number doses to the TBL region are 2.2-3.1 x 10(10) (2%) and 7.1-11. 1 x 10(5) (2%) day-1 and to the PUL region are 1.6-16.7 x 10(10) (9%) and 2.9-17.0 x 10(5) (3%) day-1. The daily surface mass dose (microg cm-2 day-1) from coarse fraction particles is large in generations 3-5. The daily number dose (particles day-1) and surface number dose (particles cm-2 day-1) are higher from the fine than the coarse fraction, by about 10(3) to 10(5) times in all lung airways. Fine fraction particles result in 10,000 times greater particle number dose per macrophage than coarse fraction particles. Particle number doses do not follow trends in mass doses, are much larger from fine than coarse fraction, and must be considered in assessing PM health

  2. Cluster analysis on mass spectra of biogenic secondary organic aerosol

    NASA Astrophysics Data System (ADS)

    Spindler, C.; Kiendler-Scharr, A.; Kleist, E.; Mensah, A.; Mentel, T.; Tillmann, R.; Wildt, J.

    2009-04-01

    Biogenic secondary organic aerosols (BSOA) are of high importance in the atmosphere. The formation of SOA from the volatile organic compound (VOC) emissions of selected trees was investigated in the JPAC (Jülich Plant Aerosol Chamber) facility. The VOC (mainly monoterpenes) were transferred into a reaction chamber where vapors were photo-chemically oxidized and formed BSOA. The aerosol was characterized by aerosol mass spectrometry (Aerodyne Quadrupol-AMS). Inside the AMS, flash-vaporization of the aerosol particles and electron impact ionization of the evaporated molecules cause a high fragmentation of the organic compounds. Here, we present a classification of the aerosol mass spectra via cluster analysis. Average mass spectra are produced by combination of related single mass spectra to so-called clusters. The mass spectra were similar due to the similarity of the precursor substances. However, we can show that there are differences in the BSOA mass spectra of different tree species. Furthermore we can distinguish the influence of the precursor chemistry and chemical aging. BSOA formed from plants exposed to stress can be distinguished from BSOA formed under non stressed conditions. Significance and limitations of the clustering method for very similar mass spectra will be demonstrated and discussed.

  3. Characterizing an extractive electrospray ionization (EESI) source for the online mass spectrometry analysis of organic aerosols.

    PubMed

    Gallimore, Peter J; Kalberer, Markus

    2013-07-01

    Organic compounds comprise a major fraction of tropospheric aerosol and understanding their chemical complexity is a key factor for determining their climate and health effects. We present and characterize here a new online technique for measuring the detailed chemical composition of organic aerosols, namely extractive electrospray ionization mass spectrometry (EESI-MS). Aerosol particles composed of soluble organic compounds were extracted into and ionized by a solvent electrospray, producing molecular ions from the aerosol with minimal fragmentation. We demonstrate here that the technique has a time resolution of seconds and is capable of making stable measurements over several hours. The ion signal in the MS was linearly correlated with the mass of aerosol delivered to the EESI source over the range tested (3-600 μg/m(3)) and was independent of particle size and liquid water content, suggesting that the entire particle bulk is extracted for analysis. Tandem MS measurements enabled detection of known analytes in the sub-μg/m(3) range. Proof-of-principle measurements of the ozonolysis of oleic acid aerosol (20 μg/m(3)) revealed the formation of a variety of oxidation products in good agreement with previous offline studies. This demonstrates the technique's potential for studying the product-resolved kinetics of aerosol-phase chemistry at a molecular level with high sensitivity and time resolution. PMID:23710930

  4. CALIPSO Observations of Near-Cloud Aerosol Properties as a Function of Cloud Fraction

    NASA Technical Reports Server (NTRS)

    Yang, Weidong; Marshak, Alexander; Varnai, Tamas; Wood, Robert

    2015-01-01

    This paper uses spaceborne lidar data to study how near-cloud aerosol statistics of attenuated backscatter depend on cloud fraction. The results for a large region around the Azores show that: (1) far-from-cloud aerosol statistics are dominated by samples from scenes with lower cloud fractions, while near-cloud aerosol statistics are dominated by samples from scenes with higher cloud fractions; (2) near-cloud enhancements of attenuated backscatter occur for any cloud fraction but are most pronounced for higher cloud fractions; (3) the difference in the enhancements for different cloud fractions is most significant within 5km from clouds; (4) near-cloud enhancements can be well approximated by logarithmic functions of cloud fraction and distance to clouds. These findings demonstrate that if variability in cloud fraction across the scenes used to composite aerosol statistics are not considered, a sampling artifact will affect these statistics calculated as a function of distance to clouds. For the Azores-region dataset examined here, this artifact occurs mostly within 5 km from clouds, and exaggerates the near-cloud enhancements of lidar backscatter and color ratio by about 30. This shows that for accurate characterization of the changes in aerosol properties with distance to clouds, it is important to account for the impact of changes in cloud fraction.

  5. COMPOSITION OF SIZE-FRACTIONATED AEROSOL IN CHARLESTON, WEST VIRGINIA

    EPA Science Inventory

    Atmospheric aerosols were collected during a 21 day period in late summer of 1976 in Charleston, West Virginia, using five dichotomous virtual impactor samplers simultaneously. The resulting coarse and fine aerosol were analyzed with a variety of physical and chemical methods: gr...

  6. Ultrahigh resolution mass spectrometric characterization of organic aerosol from European and Chinese cities

    NASA Astrophysics Data System (ADS)

    Wang, Kai; Huang, Ru-Jin; Hoffmann, Thorsten

    2016-04-01

    Organic aerosol constitutes a substantial fraction (20-90%) of submicrometer aerosol mass, playing an important role in air quality and human health. Over the past few years, ultra-high resolution mass spectrometry (UHRMS) has been applied to elucidate the chemical composition of ambient aerosols. However, most of the UHRMS studies used direct infusion without prior separation by liquid chromatography, which may cause the loss of individual compound information and interference problems. In the present study, urban ambient aerosol with particle diameter < 2.5 μm was collected in Mainz, Germany and Beijing, China, respectively. Two pretreatment procedures were applied to extract the organic compounds from the filter samples: One method uses a mixture of acetonitrile and water, the other uses pure water and prepared for the extraction of humic-like substances. The extracts were analyzed by ultra-high-performance liquid chromatography coupled with an Orbitrap mass spectrometer in both negative and the positive modes. The effects of pretreatment procedures on the characterization of organic aerosol and the city-wise difference in chemical composition of organic aerosol will be discussed in detail.

  7. ANALYSIS OF RESPIRATORY DESPOSITION DOSE OF INHALED AMBIENT AEROSOLS FOR DIFFERENT SIZE FRACTIONS

    EPA Science Inventory

    ANALYSIS OF RESPIRATORY DEPOSITION DOSE OF INHALED AMBIENT AEROSOLS FOR DIFFERENT SIZE FRACTIONS. Chong S. Kim, SC. Hu**, PA Jaques*, US EPA, National Health and Environmental Effects Research Laboratory, Research Triangle Park, NC 27711; **IIT Research Institute, Chicago, IL; *S...

  8. Non-Refractory Submicron Aerosol Mass Loadings during NEAQS

    NASA Astrophysics Data System (ADS)

    Middlebrook, A. M.; Matthew, B. M.; Canagaratna, M. R.; Worsnop, D. R.; Quinn, P. K.; Degouw, J. A.; Warneke, C.; Goldan, P. D.; Kuster, W. C.; Williams, E. J.; McKeen, S. A.

    2003-12-01

    During the New England Air Quality Study (NEAQS) in July-August 2002, an Aerosol Mass Spectrometer (AMS) was deployed aboard the NOAA ship RONALD H. BROWN and collected 2-minute averaged data. The AMS, which measures non-refractory components of aerosol particles with aerodynamic diameters between roughly 40 and 1500 nm, produced particle mass spectra as well as aerosol organic, sulfate, ammonium, and nitrate mass distributions. A wide variety of air masses were sampled, including clean marine, clean continental, and polluted continental air masses. In general, the volatile particle composition was mostly organic and sulfate with lesser amounts of ammonium and nitrate and the mass loadings typically peaked around 400-600 nm in vacuum aerodynamic diameter. Although the AMS sulfate and ammonium concentrations were highly correlated with the sulfate and ammonium concentrations from the Particle into Liquid (PILS) instrument also deployed on the ship, the AMS and PILS nitrate concentrations were not correlated and at times anti-correlated. In contrast, the AMS nitrate and organic concentrations as well as the AMS nitrate and gas phase alkyl nitrate concentrations were highly correlated. These results suggest that organic nitrate was present in the submicron aerosol phase. The AMS organic concentrations were generally higher than the AMS sulfate concentrations, consistent with other shipboard measurements. Whenever the sulfate concentration increased, the organic concentration also increased, indicating that sulfate and organic aerosol growth are influenced by the same processes or that sulfate may play a role in organic aerosol growth. The exception to this pattern occurred during a sea fog event where the sulfate concentration increased and the organic concentration decreased, probably due to rapid aqueous phase sulfur oxidation and relatively less oxidation of organic compounds. Furthermore, the organic concentration often increased without concurrent increases in

  9. On the fractional solubility of copper in marine aerosols: Toxicity of aeolian copper revisited

    NASA Astrophysics Data System (ADS)

    Sholkovitz, Edward R.; Sedwick, Peter N.; Church, Thomas M.

    2010-10-01

    Paytan et al. (2009) argue that the atmospheric deposition of aerosols lead to copper concentrations that are potentially toxic to marine phytoplankton in a large area of tropical and subtropical North Atlantic Ocean. A key assumption in their model is that all marine aerosols (mineral dust and anthropogenic particles) have a high (40%) fractional solubility of copper. Our data show that the fractional solubility of copper for Saharan dust over the Sargasso Sea and Bermuda is significantly lower (1-7%). In contrast, anthropogenic aerosols with non-Saharan sources have significantly higher values (10-100%). Hence, the potential Cu toxicity in the tropical and subtropical North Atlantic should be re-estimated, given the low fractional solubility of Cu in the Saharan dust that dominates aerosol deposition to this region.

  10. Ambient aerosol analysis using aerosol-time-of-flight mass spectrometry

    SciTech Connect

    Prather, K.A.; Noble, C.A.; Liu, D.Y.; Silva, P.J.; Fergenson, D.F.

    1996-10-01

    We have recently developed a technique, Aerosol-Time-of-Flight Mass Spectrometry (ATOFMS), which is capable of real-time determination of the aerodynamic size and chemical composition of individual aerosol particles. In order to obtain such information, the techniques of aerodynamic particle sizing and time-of-flight mass spectrometry are combined in a single instrument. ATOFMS is being used for the direct analysis of ambient aerosols with the goal of establishing correlations between particle size and chemical composition. Currently, measurements are being made to establish potential links between the presence of particular types of particles with such factors as the time of day, weather conditions, and concentration levels of gaseous smog components such as NO{sub x} and ozone. This data will be used to help establish a better understanding of tropospheric gas-aerosol processes. This talk will discuss the operating principles of ATOFMS as well as present the results of ambient analysis studies performed in our laboratory.

  11. Overview of submicron aerosol characterization in China using an Aerodyne high-resolution aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Huang, X.; He, L.; Gong, Z.; Hu, M.; Zhang, Y.

    2011-12-01

    China is one of the most rapidly developing countries in the world, but in the meantime it is suffering from severe air pollution due to heavy industrial/metropolitan emissions. Most previous aerosol studies in China were based on filter sampling followed by laboratory analysis, which provided datasets at a coarse time resolution like a day. The coarse time resolution of the aerosol datasets cannot match the actual faster variation of aerosol properties in the real atmosphere, which strongly favors highly time-resolved on-line measurement techniques. In recent years, our group deployed an Aerodyne high-resolution aerosol mass spectrometer (AMS) in different ambient atmospheres in China, including Beijing (urban), Shanghai (urban), Shenzhen (urban), Jiaxing (suburban), and Kaiping (rural). In this presentation, we will overview these on-line AMS measurement results to characterize the properties of submicron particles in China atmosphere, such as chemical composition, size distribution, diurnal variation, elemental composition, primary and secondary organic aerosol constitution, etc. The newly-developed AMS-PMF modeling techniques were utilized to quantitatively differentiate the contributions from fossil fuel combustion, cooking emissions, biomass burning, as well as secondary organic aerosol to ambient organic aerosol loadings in China. These AMS results have provided new outlook of the formation mechanisms of high aerosol pollution in China.

  12. Characterization of urban aerosol using aerosol mass spectrometry and proton nuclear magnetic resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    Cleveland, M. J.; Ziemba, L. D.; Griffin, R. J.; Dibb, J. E.; Anderson, C. H.; Lefer, B.; Rappenglück, B.

    2012-07-01

    Particulate matter was measured during August and September of 2006 in Houston as part of the Texas Air Quality Study II Radical and Aerosol Measurement Project. Aerosol size and composition were determined using an Aerodyne quadrupole aerosol mass spectrometer. Aerosol was dominated by sulfate (4.1 ± 2.6 μg m-3) and organic material (5.5 ± 4.0 μg m-3), with contributions of organic material from both primary (˜32%) and secondary (˜68%) sources. Secondary organic aerosol appears to be formed locally. In addition, 29 aerosol filter samples were analyzed using proton nuclear magnetic resonance (1H NMR) spectroscopy to determine relative concentrations of organic functional groups. Houston aerosols are less oxidized than those observed elsewhere, with smaller relative contributions of carbon-oxygen double bonds. These particles do not fit 1H NMR source apportionment fingerprints for identification of secondary, marine, and biomass burning organic aerosol, suggesting that a new fingerprint for highly urbanized and industrially influenced locations be established.

  13. Urban increments of gaseous and aerosol pollutants and their sources using mobile aerosol mass spectrometry measurements

    NASA Astrophysics Data System (ADS)

    Elser, Miriam; Bozzetti, Carlo; El-Haddad, Imad; Maasikmets, Marek; Teinemaa, Erik; Richter, Rene; Wolf, Robert; Slowik, Jay G.; Baltensperger, Urs; Prévôt, André S. H.

    2016-06-01

    Air pollution is one of the main environmental concerns in urban areas, where anthropogenic emissions strongly affect air quality. This work presents the first spatially resolved detailed characterization of PM2.5 (particulate matter with aerodynamic equivalent diameter daero ≤ 2.5 µm) in two major Estonian cities, Tallinn and Tartu. The measurements were performed in March 2014 using a mobile platform. In both cities, the non-refractory (NR)-PM2.5 was characterized by a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) using a recently developed lens which increases the transmission of super-micron particles. Equivalent black carbon (eBC) and several trace gases including carbon monoxide (CO), carbon dioxide (CO2), and methane (CH4) were also measured. The chemical composition of PM2.5 was found to be very similar in the two cities. Organic aerosol (OA) constituted the largest fraction, explaining on average about 52 to 60 % of the PM2.5 mass. Four sources of OA were identified using positive matrix factorization (PMF): hydrocarbon-like OA (HOA, from traffic emissions), biomass burning OA (BBOA, from biomass combustion), residential influenced OA (RIOA, probably mostly from cooking processes with possible contributions from waste and coal burning), and oxygenated OA (OOA, related to secondary aerosol formation). OOA was the major OA source during nighttime, explaining on average half of the OA mass, while during daytime mobile measurements the OA was affected by point sources and dominated by the primary fraction. A strong increase in the secondary organic and inorganic components was observed during periods with transport of air masses from northern Germany, while the primary local emissions accumulated during periods with temperature inversions. Mobile measurements offered the identification of different source regions within the urban areas and the assessment of the extent to which pollutants concentrations exceeded regional background

  14. Investigating Types and Sources of Organic Aerosol in Rocky Mountain National Park Using Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Schurman, M. I.; Lee, T.; Sun, Y.; Schichtel, B. A.; Kreidenweis, S. M.; Collett, J. L.

    2011-12-01

    The Rocky Mountain Atmospheric Nitrogen and Sulfur Study (RoMANS) focuses on identifying pathways and sources of nitrogen deposition in Rocky Mountain National Park (RMNP). Past work has combined measurements from a range of instrumentation such as annular denuders, PILS-IC, Hi-Vol samplers, and trace gas analyzers. Limited information from early RoMANS campaigns is available regarding organic aerosol. While prior measurements have produced a measure of total organic carbon mass, high time resolution measures of organic aerosol concentration and speciation are lacking. One area of particular interest is characterizing the types, sources, and amounts of organic nitrogen aerosol. Organic nitrogen measurements in RMNP wet deposition reveal a substantial contribution to the total reactive nitrogen deposition budget. In this study an Aerodyne High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) was deployed in summer 2010 at RMNP to investigate organic aerosol composition and its temporal variability. The species timeline and diurnal species variations are combined with meteorological data to investigate local transport events and chemistry; transport from the Colorado Front Range urban corridor appears to be more significant for inorganic species than for the overall organic aerosol mass. Considerable variation in organic aerosol concentration is observed (0.5 to 20 μg/m3), with high concentration episodes lasting between hours and two days. High resolution AMS data are analyzed for organic aerosol, including organic nitrogen species that might be expected from local biogenic emissions, agricultural activities, and secondary reaction products of combustion emissions. Positive matrix factorization reveals that semi-volatile oxidized OA, low-volatility oxidized OA, and biomass burning OA comprise most organic mass; the diurnal profile of biomass burning OA peaks at four and nine pm and may arise from local camp fires, while constant concentrations of

  15. Distribution of 7Be, 210Pb and 210Po in Size Fractionated Aerosols From Northern Taiwan

    NASA Astrophysics Data System (ADS)

    Su, C.; Huh, C.

    2003-12-01

    The partition of 7Be, 210Pb and 210Po in size fractionated aerosols was studied using samples collected from Nankang (northern Taiwan) during July 2002-July 2003. A TSP air sampler coupled to a 6-stage cascade impactor was used to collect large-volume samples and separate the aerosols into six size classes with the cut-off points at 7.2 μ m, 3 μ m, 1.5 μ m, 0.95 μ m and 0.49 μ m. The total mass concentrations of the aerosol samples ranged from 23 to 99 μ g m-3, with a maximum (18-50 %) falling at the sixth stage (< 0.49 μ m) and a minimum (5-13 %) at the third stage (1.5-3.0 μ m). Total concentrations of 7Be, 210Pb and 210Po in the samples were 0.11-0.56, 0.012-0.100 and 0.0009-0.0158 dpm m-3, respectively. For most of the samples, more than 70 % of the radioactivities are found in the fifth and sixth stages (< 0.95 μ m). Concurrent with the measurements of 7Be and 210Pb concentrations in aerosols, we have also measured the fluxes of these nuclides. Coupling the concentration data with the flux data, we obtained an overall deposition velocity of 0.02-3.71 cm s-1 for 7Be and 0.09-6.18 cm s-1 for 210Pb, without any obvious seasonal variation during the experimental periods. The size of aerosol particles and the height of cloud are the major factors controlling the deposition velocity of 7Be and 210Pb. The time series of 210Po/210Pb was in phase with that of 7Be/210Pb and showed an increase during the spring and summer, probably reflecting stratospheric folding in the spring and more vigorous tropospheric mixing (e.g., due to typhoons) in the summer.

  16. Characterization of near-highway submicron aerosols in New York City with a high-resolution aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Sun, Y. L.; Zhang, Q.; Schwab, J. J.; Chen, W.-N.; Bae, M.-S.; Hung, H.-M.; Lin, Y.-C.; Ng, N. L.; Jayne, J.; Massoli, P.; Williams, L. R.; Demerjian, K. L.

    2012-02-01

    Knowledge of the variations of mass concentration, chemical composition and size distributions of submicron aerosols near roadways is of importance for reducing exposure assessment uncertainties in health effects studies. The goal of this study is to deploy and evaluate an Atmospheric Sciences Research Center-Mobile Laboratory (ASRC-ML), equipped with a suite of rapid response instruments for characterization of traffic plumes, adjacent to the Long Island Expressway (LIE) - a high-traffic highway in the New York City Metropolitan Area. In total, four measurement periods, two in the morning and two in the evening were conducted at a location approximately 30 m south of the LIE. The mass concentrations and size distributions of non-refractory submicron aerosol (NR-PM1) species were measured in situ at a time resolution of 1 min by an Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer, along with rapid measurements (down to 1 Hz) of gaseous pollutants (e.g. HCHO, NO2, NO, O3, and CO2, etc.), black carbon (BC), and particle number concentrations and size distributions. Particulate organics varied dramatically during periods with high traffic influences from the nearby roadway. The variations were mainly observed in the hydrocarbon-like organic aerosol (HOA), a surrogate for primary OA from vehicle emissions. The inorganic species (sulfate, ammonium, and nitrate) and oxygenated OA (OOA) showed much smoother variations indicating minor impacts from traffic emissions. The concentration and chemical composition of NR-PM1 also varied differently on different days depending on meteorology, traffic intensity and vehicle types. Overall, organics dominated the traffic-related NR-PM1 composition (>60%) with HOA accounting for a major fraction of OA. The traffic-influenced organics showed two distinct modes in mass-weighted size distributions, peaking at ∼120 nm and 500 nm (vacuum aerodynamic diameter, Dva), respectively. OOA and inorganic species appear to be

  17. Aerosol detection efficiency in inductively coupled plasma mass spectrometry

    DOE PAGESBeta

    Hubbard, Joshua A.; Zigmond, Joseph A.

    2016-03-02

    We used an electrostatic size classification technique to segregate particles of known composition prior to being injected into an inductively coupled plasma mass spectrometer (ICP-MS). Moreover, we counted size-segregated particles with a condensation nuclei counter as well as sampled with an ICP-MS. By injecting particles of known size, composition, and aerosol concentration into the ICP-MS, efficiencies of the order of magnitude aerosol detection were calculated, and the particle size dependencies for volatile and refractory species were quantified. Similar to laser ablation ICP-MS, aerosol detection efficiency was defined as the rate at which atoms were detected in the ICP-MS normalized bymore » the rate at which atoms were injected in the form of particles. This method adds valuable insight into the development of technologies like laser ablation ICP-MS where aerosol particles (of relatively unknown size and gas concentration) are generated during ablation and then transported into the plasma of an ICP-MS. In this study, we characterized aerosol detection efficiencies of volatile species gold and silver along with refractory species aluminum oxide, cerium oxide, and yttrium oxide. Aerosols were generated with electrical mobility diameters ranging from 100 to 1000 nm. In general, it was observed that refractory species had lower aerosol detection efficiencies than volatile species, and there were strong dependencies on particle size and plasma torch residence time. Volatile species showed a distinct transition point at which aerosol detection efficiency began decreasing with increasing particle size. This critical diameter indicated the largest particle size for which complete particle detection should be expected and agreed with theories published in other works. Aerosol detection efficiencies also displayed power law dependencies on particle size. Aerosol detection efficiencies ranged from 10-5 to 10-11. Free molecular heat and mass transfer theory was

  18. Aerosol detection efficiency in inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Hubbard, Joshua A.; Zigmond, Joseph A.

    2016-05-01

    An electrostatic size classification technique was used to segregate particles of known composition prior to being injected into an inductively coupled plasma mass spectrometer (ICP-MS). Size-segregated particles were counted with a condensation nuclei counter as well as sampled with an ICP-MS. By injecting particles of known size, composition, and aerosol concentration into the ICP-MS, efficiencies of the order of magnitude aerosol detection were calculated, and the particle size dependencies for volatile and refractory species were quantified. Similar to laser ablation ICP-MS, aerosol detection efficiency was defined as the rate at which atoms were detected in the ICP-MS normalized by the rate at which atoms were injected in the form of particles. This method adds valuable insight into the development of technologies like laser ablation ICP-MS where aerosol particles (of relatively unknown size and gas concentration) are generated during ablation and then transported into the plasma of an ICP-MS. In this study, we characterized aerosol detection efficiencies of volatile species gold and silver along with refractory species aluminum oxide, cerium oxide, and yttrium oxide. Aerosols were generated with electrical mobility diameters ranging from 100 to 1000 nm. In general, it was observed that refractory species had lower aerosol detection efficiencies than volatile species, and there were strong dependencies on particle size and plasma torch residence time. Volatile species showed a distinct transition point at which aerosol detection efficiency began decreasing with increasing particle size. This critical diameter indicated the largest particle size for which complete particle detection should be expected and agreed with theories published in other works. Aerosol detection efficiencies also displayed power law dependencies on particle size. Aerosol detection efficiencies ranged from 10- 5 to 10- 11. Free molecular heat and mass transfer theory was applied, but

  19. Characterization of saccharides in size-fractionated ambient particulate matter and aerosol sources: the contribution of primary biological aerosol particles (PBAPs) and soil to ambient particulate matter.

    PubMed

    Jia, Yuling; Fraser, Matthew

    2011-02-01

    Size-fractionated (equivalent to ambient PM2.5 and PM10) local soil, plant, and spore samples were collected in the Sonoran Desert near Phoenix, AZ and measured for saccharide content with the goal of characterizing ambient particulate matter sources including soil and primary biological aerosol particles (PBAPs) from plants and fungi. Different saccharide compositions were observed among soil, plant, and spore samples and between PM2.5 and PM10 fractions. The total measured nonlevoglucosan saccharide content relative to PM mass in ambient aerosols collected in a Phoenix suburb (Higley) was much higher compared to the local soil samples but much lower compared to the PBAP. The enrichment of saccharides from two saccharide-dominated PM source factors resolved by a positive matrix factorization model is also higher than the saccharide content in the size-fractionated local soil samples, but lower than that measured in the size-segregated PBAP samples. This indicates that ambient concentration of particulate saccharides at Higley was dominated by contributions from PBAPs directly injected into the atmosphere from plants and spores rather than from soil and associated biota. Our results also suggest the contribution to the fine size fraction of ambient PM from the primary biologically derived sources may be greater than previously acknowledged. PMID:21214236

  20. Detailed mass size distributions of elements and species, and aerosol chemical mass closure during fall 1999 at Gent, Belgium

    NASA Astrophysics Data System (ADS)

    Maenhaut, Willy; Cafmeyer, Jan; Dubtsov, Sergei; Chi, Xuguang

    2002-04-01

    A 10-stage microorifice uniform deposit impactor (MOUDI) and a 12-stage small deposit area low pressure impactor (SDI) were operated at Gent from 6 September to 30 October 1999. Thirty-four parallel samples (of typically 24 h) were collected. The MOUDI samples were analysed for the particulate mass (PM) by weighing, and for organic carbon (OC) and elemental carbon (EC) by a thermal-optical transmission technique. The SDI samples were analysed for 27 elements by PIXE. PM and OC exhibited typically a rather similar bimodal size distribution, with most of their mass in the submicrometer size range. EC was predominantly associated with fine particles, with maximum typically at around 0.2 μm equivalent aerodynamic diameter (EAD). Sulphur was also mainly in the fine size range, but with maximum at 0.5 μm EAD. Other elements with mainly a fine mode were V, Ni, As, Se and Pb. The crustal elements (Al, Si, Ti, Fe, Zr) exhibited mostly a unimodal coarse mode size distribution, with maximum at about 4 μm EAD. Other elements with mainly a coarse mode were Na, Mg, P, Ca, Cr, Mn, Cu, Ga and Sr. The elements K, Zn and Rb were generally bimodal. Aerosol chemical mass closure calculations indicated that organic aerosol and crustal matter were the major aerosol types in the supermicrometer size range, and that the dominant aerosol types in the submicrometer fraction were organic aerosol and sulphate. On average, 74% of the gravimetric PM was accounted for by the aerosol types considered.

  1. Submicron aerosol mass balance at urban and semirural sites in the Milan area (Italy)

    NASA Astrophysics Data System (ADS)

    Putaud, J. P.; van Dingenen, Rita; Raes, Frank

    2002-11-01

    During the Pianura Padana Produzione di Ozono (PIPAPO) field campaign (May-June 1998), aerosol measurements were performed at an urban site and a semirural site to determine the particulate matter chemical composition in the Milan area. Aerosol samples were collected on filters for subsequent chemical analysis using virtual impactors. Possible sampling artifacts for semivolatile particulate species were addressed. Our NH4NO3 measurements were successfully compared with artifact free wet denuder-wet aerosol collector sampler data. Positive sampling artifacts for organic species were corrected using the back-to-back filter technique, allowing us to assess the lower limit for particulate organic carbon (POC) concentrations. Aerosol size distributions were measured on-line with differential mobility analyzers (DMA). The variations in the submicron aerosol mass concentration estimated from chemical analyses compared well with the variations in the submicron particle volume calculated from number size distributions. At both sites, 70% of the PM10 mass was found in the submicron fraction. The mean submicron aerosol mass concentrations were 28 μg m-3 and 20 μg m-3 at the urban site and the semirural site, respectively. The correlations between NH4+ and NO3- + 2SO4= indicate that strong acids were fully neutralized at both sites. At the urban site the submicron concentrations of NH4NO3, (NH4)2SO4, and POC were 8.1 μg m-3, 6.3 μg m-3, and 6.4 μgC m-3, respectively. At the semi-rural site, these concentrations were 4.9 μg m-3, 4.0 μg m-3, and 5.6 μgC m-3, respectively. These results show that sulfate and nitrate contribute about the same amount to submicron aerosol mass concentration, and that particulate organic matter (POM) could be the major component of the aerosol submicron mass in the Milan region, especially in semirural areas. The correlation between normalized concentrations of POM and O3 observed at the semirural site suggests that POM results at least

  2. A physically based framework for modeling the organic fractionation of sea spray aerosol from bubble film Langmuir equilibria

    NASA Astrophysics Data System (ADS)

    Burrows, S. M.; Ogunro, O.; Frossard, A. A.; Russell, L. M.; Rasch, P. J.; Elliott, S. M.

    2014-12-01

    The presence of a large fraction of organic matter in primary sea spray aerosol (SSA) can strongly affect its cloud condensation nuclei activity and interactions with marine clouds. Global climate models require new parameterizations of the SSA composition in order to improve the representation of these processes. Existing proposals for such a parameterization use remotely sensed chlorophyll a concentrations as a proxy for the biogenic contribution to the aerosol. However, both observations and theoretical considerations suggest that existing relationships with chlorophyll a, derived from observations at only a few locations, may not be representative for all ocean regions. We introduce a novel framework for parameterizing the fractionation of marine organic matter into SSA based on a competitive Langmuir adsorption equilibrium at bubble surfaces. Marine organic matter is partitioned into classes with differing molecular weights, surface excesses, and Langmuir adsorption parameters. The classes include a lipid-like mixture associated with labile dissolved organic carbon (DOC), a polysaccharide-like mixture associated primarily with semilabile DOC, a protein-like mixture with concentrations intermediate between lipids and polysaccharides, a processed mixture associated with recalcitrant surface DOC, and a deep abyssal humic-like mixture. Box model calculations have been performed for several cases of organic adsorption to illustrate the underlying concepts. We then apply the framework to output from a global marine biogeochemistry model, by partitioning total dissolved organic carbon into several classes of macromolecules. Each class is represented by model compounds with physical and chemical properties based on existing laboratory data. This allows us to globally map the predicted organic mass fraction of the nascent submicron sea spray aerosol. Predicted relationships between chlorophyll a and organic fraction are similar to existing empirical parameterizations

  3. Characterization of ambient aerosols at the San Francisco International Airport using BioAerosol Mass Spectrometry

    SciTech Connect

    Steele, P T; McJimpsey, E L; Coffee, K R; Fergenson, D P; Riot, V J; Tobias, H J; Woods, B W; Gard, E E; Frank, M

    2006-03-16

    The BioAerosol Mass Spectrometry (BAMS) system is a rapidly fieldable, fully autonomous instrument that can perform correlated measurements of multiple orthogonal properties of individual aerosol particles. The BAMS front end uses optical techniques to nondestructively measure a particle's aerodynamic diameter and fluorescence properties. Fluorescence can be excited at 266nm or 355nm and is detected in two broad wavelength bands. Individual particles with appropriate size and fluorescence properties can then be analyzed more thoroughly in a dual-polarity time-of-flight mass spectrometer. Over the course of two deployments to the San Francisco International Airport, more than 6.5 million individual aerosol particles were fully analyzed by the system. Analysis of the resulting data has provided a number of important insights relevant to rapid bioaerosol detection, which are described here.

  4. Identification and quantification of organic aerosol from cooking and other sources in Barcelona using aerosol mass spectrometer data

    NASA Astrophysics Data System (ADS)

    Mohr, C.; Decarlo, P. F.; Heringa, M. F.; Chirico, R.; Slowik, J. G.; Richter, R.; Reche, C.; Alastuey, A.; Querol, X.; Seco, R.; Peñuelas, J.; Jiménez, J. L.; Crippa, M.; Zimmermann, R.; Baltensperger, U.; Prévôt, A. S. H.

    2011-10-01

    PM1 (particulate matter with an aerodynamic diameter <1 μm) non-refractory components and black carbon were measured continuously together with additional parameters at an urban background site in Barcelona, Spain, during March 2009 (campaign DAURE, Determination of the sources of atmospheric Aerosols in Urban and Rural Environments in the western Mediterranean). Positive matrix factorization (PMF) was conducted on the organic aerosol (OA) data matrix measured by an aerosol mass spectrometer, on both unit mass (UMR) and high resolution (HR) data. Five factors or sources could be identified: LV-OOA (low-volatility oxygenated OA), related to regional, aged secondary OA; SV-OOA (semi-volatile oxygenated OA), a fresher oxygenated OA; HOA (hydrocarbon-like OA, related to traffic emissions); BBOA (biomass burning OA) from domestic heating or agricultural biomass burning activities; and COA (cooking OA). LV-OOA contributed 28% to OA, SV-OOA 27%, COA 17%, HOA 16%, and BBOA 11%. The COA HR spectrum contained substantial signal from oxygenated ions (O/C: 0.21) whereas the HR HOA spectrum had almost exclusively contributions from chemically reduced ions (O/C: 0.03). If we assume that the carbon in HOA is fossil while that in COA and BBOA is modern, primary OA in Barcelona contains a surprisingly high fraction (59%) of non-fossil carbon. This paper presents a method for estimating cooking organic aerosol in ambient datasets based on the fractions of organic mass fragments at m/z 55 and 57: their data points fall into a V-shape in a scatter plot, with strongly influenced HOA data aligned to the right arm and strongly influenced COA data points aligned to the left arm. HR data show that this differentiation is mainly driven by the oxygen-containing ions C3H3O+ and C3H5O+, even though their contributions to m/z 55 and 57 are low compared to the reduced ions C4H7+ and C4H9+. A simple estimation method based on the organic mass fragments at m/z 55, 57, and 44 is developed here and

  5. MASS SPECTROMETRY OF INDIVIDUAL AEROSOL PARTICLES. (R823980)

    EPA Science Inventory

    Typically, in real-time aerosol mass spectrometry (RTAMS), individual airborne particles
    are ablated and ionized with a single focused laser pulse. This technique yields information that
    permits bulk characterization of the particle, but information about the particle's sur...

  6. THE MASS ACCOMMODATION COEFFICIENT OF AMMONIUM NITRATE AEROSOL. (R823514)

    EPA Science Inventory

    The mass transfer rate of pure ammonium nitrate between the aerosol and gas phases was
    quantified experimentally by the use of the tandem differential mobility analyzer/scanning mobility
    particle sizer (TDMA/SMPS) technique. Ammonium nitrate particles 80-220 nm in diameter<...

  7. Aerosol mass spectrometry systems and methods

    SciTech Connect

    Fergenson, David P.; Gard, Eric E.

    2013-08-20

    A system according to one embodiment includes a particle accelerator that directs a succession of polydisperse aerosol particles along a predetermined particle path; multiple tracking lasers for generating beams of light across the particle path; an optical detector positioned adjacent the particle path for detecting impingement of the beams of light on individual particles; a desorption laser for generating a beam of desorbing light across the particle path about coaxial with a beam of light produced by one of the tracking lasers; and a controller, responsive to detection of a signal produced by the optical detector, that controls the desorption laser to generate the beam of desorbing light. Additional systems and methods are also disclosed.

  8. The Mass-Dependence of Cadmium Isotope Fractionation During Evaporation

    NASA Astrophysics Data System (ADS)

    Rehkamper, M.; Wombacher, F.; Mezger, K.; Wiechert, U.

    2002-12-01

    Isotope fractionation laws relate the isotope fractionation factor αA of one isotope ratio to the fractionation factor αB of a second isotope ratio of the same element with a fractionation exponent β, such that αA = αBβ. In a recent paper, Young et al. (GCA 66, 1095-1104 (2002)) inferred that kinetic and equilibrium isotope fractionations are characterized by different mass functions, such that βkin is not equal to βeq. As a consequence, kinetic isotope fractionation is expected to produce fractionation lines in three isotope space that are different from those generated by equilibrium fractionation processes. Young et al. furthermore stated that the variability in mass-dependent fractionation laws may be sufficient to account for the negative Δ17O of tropospheric O2 and the Δ17O anomalies of minerals in SNC meteorites. Such variations have otherwise been interpreted as evidence of non-mass dependant isotope fractionations (Luz et al., Nature 400, 547-550 (1999); Farquhar et al., Science 280, 1589-1582 (1998)). In the present study, we investigated the mass-dependence of isotope fractionation by evaluating the results of evaporation experiments that produced very large differences in Cd isotope compositions (up to about 100‰ ). In these experiments, liquid Cd was evaporated into a vacuum at a temperature of about 200°C. The metal residues remaining after evaporation were analyzed for their Cd isotope composition by multiple-collector inductively coupled plasma-mass spectrometry (MC-ICPMS) relative to the unfractionated starting material. The precision of the measurements is sufficient to clearly distinguish between different fractionation mechanisms. In linearized three-isotope space, the residual Cd metals plot on fractionation lines (e.g., with a slope β = 2.049 +/- 2 for 106}Cd/{114Cd vs. 110}Cd/{114Cd) that are intermediate between the kinetic (β = 2.036) and the equilibrium (β = 2.075) fractionation lines. This can be explained by an

  9. Evaluation of the performance of the determination of anions in the water soluble fraction of atmospheric aerosols.

    PubMed

    Arias, Alejandro; Bettencourt da Silva, Ricardo J N; Camões, M Filomena G F C; Oliveira, Cristina M R R

    2013-01-30

    The knowledge of the mass of particulate matter in air, its chemical composition and emission sources is of relevance for taking decisions concerning air quality management in urban areas. The interpretation of these data is a function of the quality of the measurement results expressed by their uncertainties. This study aimed at developing models of the performance of the determination of anions in the water-soluble fraction of atmospheric aerosols, capable of determining, separately, the contribution of aerosols sampling, extraction of water-soluble fraction of atmospheric aerosols and quantification, by ion chromatography, of anions in the extract. The sampling procedure was assessed from the dispersion of results of duplicate parallel sampling after subtracting the analytical component of this dispersion. These models are used to evaluate the adequacy of the measurement procedure for the determination of urban aerosol composition and to support strategies for reducing measurement uncertainty or cost of analysis. The method performance was studied for the following ranges considering extract dilution up to five times: 0.23-8 μg m(-3) for chloride and nitrate, and 0.093-3.25 μg m(-3) for sulphate. Measurements are fit for the analysis of urban aerosols since the relative expanded measurement uncertainty is smaller than a maximum value of 40%. The percentage contribution of the uncertainty components varies with the analyte and its mass concentration, the major components being 24-93% for the extraction, 43-59% for sampling, 0.2-28% for the interpolation of the sample signal in the calibration curve and 4-8% for air volume measurement. The typical composition of analysed air is: (1.12±0.26) μg m(-3), (1.02±0.30) μg m(-3) and (0.76±0.22) μg m(-3) of chloride, nitrate and sulphate in the water soluble fraction of aerosol, respectively, for a confidence level of approximately 95% considering a coverage factor of 2. PMID:23597881

  10. Identification and quantification of organic aerosol from cooking and other sources in Barcelona using aerosol mass spectrometer data

    NASA Astrophysics Data System (ADS)

    Mohr, C.; Decarlo, P. F.; Heringa, M. F.; Chirico, R.; Slowik, J. G.; Richter, R.; Reche, C.; Alastuey, A.; Querol, X.; Seco, R.; Peñuelas, J.; Jiménez, J. L.; Crippa, M.; Zimmermann, R.; Baltensperger, U.; Prévôt, A. S. H.

    2012-02-01

    PM1 (particulate matter with an aerodynamic diameter <1 μm) non-refractory components and black carbon were measured continuously together with additional air quality and atmospheric parameters at an urban background site in Barcelona, Spain, during March 2009 (campaign DAURE, Determination of the sources of atmospheric Aerosols in Urban and Rural Environments in the western Mediterranean). Positive matrix factorization (PMF) was conducted on the organic aerosol (OA) data matrix measured by an aerosol mass spectrometer, on both unit mass (UMR) and high resolution (HR) data. Five factors or sources could be identified: LV-OOA (low-volatility oxygenated OA), related to regional, aged secondary OA; SV-OOA (semi-volatile oxygenated OA), a fresher oxygenated OA; HOA (hydrocarbon-like OA, related to traffic emissions); BBOA (biomass burning OA) from domestic heating or agricultural biomass burning activities; and COA (cooking OA). LV-OOA contributed 28% to OA, SV-OOA 27%, COA 17%, HOA 16%, and BBOA 11%. The COA HR spectrum contained substantial signal from oxygenated ions (O:C: 0.21) whereas the HR HOA spectrum had almost exclusively contributions from chemically reduced ions (O:C: 0.03). If we assume that the carbon in HOA is fossil while that in COA and BBOA is modern, primary OA in Barcelona contains a surprisingly high fraction (59%) of non-fossil carbon. This paper presents a method for estimating cooking organic aerosol in ambient datasets based on the fractions of organic mass fragments at m/z 55 and 57: their data points fall into a V-shape in a scatter plot, with strongly influenced HOA data aligned to the right arm and strongly influenced COA data points aligned to the left arm. HR data show that this differentiation is mainly driven by the oxygen-containing ions C3H3O+ and C3H5O+, even though their contributions to m/z 55 and 57 are low compared to the reduced ions C4H7+ and C4H9+. A simple estimation method based on the markers m/z 55, 57, and 44 is

  11. Molecular Characterization of Nitrogen Containing Organic Compounds in Biomass Burning Aerosols Using High Resolution Mass Spectrometry

    SciTech Connect

    Laskin, Alexander; Smith, Jeffrey S.; Laskin, Julia

    2009-05-13

    Although nitrogen-containing organic compounds (NOC) are important components of atmospheric aerosols, little is known about their chemical compositions. Here we present detailed characterization of the NOC constituents of biomass burning aerosol (BBA) samples using high resolution electrospray ionization mass spectrometry (ESI/MS). Accurate mass measurements combined with MS/MS fragmentation experiments of selected ions were used to assign molecular structures to individual NOC species. Our results indicate that N-heterocyclic alkaloid compounds - species naturally produced by plants and living organisms - comprise a substantial fraction of NOC in BBA samples collected from test burns of five biomass fuels. High abundance of alkaloids in test burns of ponderosa pine - a widespread tree in the western U.S. areas frequently affected by large scale fires - suggests that N-heterocyclic alkaloids in BBA can play a significant role in dry and wet deposition of fixed nitrogen in this region.

  12. The Impact of Atmospheric Aerosols on the Fraction of absorbed Photosynthetically Active Radiation

    NASA Astrophysics Data System (ADS)

    Veroustraete, Frank

    2010-05-01

    Aerosol pollution attracts a growing interest from atmospheric scientists with regard to their impact on health, the global climate and vegetation stress. A hypothesis, less investigated, is whether atmospheric aerosol interactions in the solar radiation field affect the amount of radiation absorbed by vegetation canopies and hence terrestrial vegetation productivity. Typically, aerosols affect vegetation canopy radiation absorption efficiency by altering the physical characteristics of solar radiation incoming on for example a forest canopy. It has been illustrated, that increasing mixing ratio's of atmospheric particulate matter lead to a higher fraction of diffuse sunlight as opposed to direct sunlight. It can be demonstrated, based on the application of atmospheric (MODTRAN) and leaf/canopy radiative transfer (LIBERTY/SPRINT) models, that radiation absorption efficiency in the PAR band of Picea like forests increases with increasing levels of diffuse radiation. It can be documented - on a theoretical basis - as well, that increasing aerosol loads in the atmosphere, induce and increased canopy PAR absorption efficiency. In this paper it is suggested, that atmospheric aerosols have to be taken into account when estimating vegetation gross primary productivity (GPP). The results suggest that Northern hemisphere vegetation CO2 uptake magnitude may increase with increasing atmospheric aerosol loads. Many climate impact scenario's related to vegetation productivity estimates, do not take this phenomenon into account. Boldly speaking, the results suggest a larger sink function for terrestrial vegetation than generally accepted. Keywords: Aerosols, vegetation, fAPAR, CO2 uptake, diffuse radiation.

  13. Mass spectroscopy of single aerosols from field measurements

    SciTech Connect

    Thomson, D.S.; Murphy, D.M.

    1995-12-31

    We are developing an aircraft instrument for the chemical analysis of individual ambient aerosols in real time. In order to test the laboratory version of this instrument, we participated in a field campaign near the continental divide in Colorado in September, 1993. During this campaign, over 5000 mass spectra of ambient aerosols were collected. Analysis of the negative ion spectra shows that sulfate was the most commonly seen component of smaller particles, while nitrate was more common in larger particles. Organic compounds are present in most particles, and we believe we can distinguish inorganic carbon in some particles. Although numerous distinct classes of particles were observed, indicating external mixtures, almost all of these particle types were themselves mixtures of several compounds. Finally, we note that although the field site experienced distinct polluted and unpolluted episodes, aerosol composition did not correlate with gas phase chemistry.

  14. Derivation of Aerosol Columnar Mass from MODIS Optical Depth

    NASA Technical Reports Server (NTRS)

    Gasso, Santiago; Hegg, Dean A.

    2003-01-01

    In order to verify performance, aerosol transport models (ATM) compare aerosol columnar mass (ACM) with those derived from satellite measurements. The comparison is inherently indirect since satellites derive optical depths and they use a proportionality constant to derive the ACM. Analogously, ATMs output a four dimensional ACM distribution and the optical depth is linearly derived. In both cases, the proportionality constant requires a direct intervention of the user by prescribing the aerosol composition and size distribution. This study introduces a method that minimizes the direct user intervention by making use of the new aerosol products of MODIS. A parameterization is introduced for the derivation of columnar aerosol mass (AMC) and CCN concentration (CCNC) and comparisons between sunphotometer, MODIS Airborne Simulator (MAS) and in-measurements are shown. The method still relies on the scaling between AMC and optical depth but the proportionality constant is dependent on the MODIS derived r$_{eff}$,\\eta (contribution of the accumulation mode radiance to the total radiance), ambient RH and an assumed constant aerosol composition. The CCNC is derived fkom a recent parameterization of CCNC as a function of the retrieved aerosol volume. By comparing with in-situ data (ACE-2 and TARFOX campaigns), it is shown that retrievals in dry ambient conditions (dust) are improved when using a proportionality constant dependent on r$ {eff}$ and \\eta derived in the same pixel. In high humidity environments, the improvement inthe new method is inconclusive because of the difficulty in accounting for the uneven vertical distribution of relative humidity. Additionally, two detailed comparisons of AMC and CCNC retrieved by the MAS algorithm and the new method are shown. The new method and MAS retrievals of AMC are within the same order of magnitude with respect to the in-situ measurements of aerosol mass. However, the proposed method is closer to the in-situ measurements than

  15. Organic aerosol mixing observed by single-particle mass spectrometry.

    PubMed

    Robinson, Ellis Shipley; Saleh, Rawad; Donahue, Neil M

    2013-12-27

    We present direct measurements of mixing between separately prepared organic aerosol populations in a smog chamber using single-particle mass spectra from the high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). Docosane and docosane-d46 (22 carbon linear solid alkane) did not show any signs of mixing, but squalane and squalane-d62 (30 carbon branched liquid alkane) mixed on the time scale expected from a condensational-mixing model. Docosane and docosane-d46 were driven to mix when the chamber temperature was elevated above the melting point for docosane. Docosane vapors were shown to mix into squalane-d62, but not the other way around. These results are consistent with low diffusivity in the solid phase of docosane particles. We performed mixing experiments on secondary organic aerosol (SOA) surrogate systems finding that SOA derived from toluene-d8 (a surrogate for anthropogenic SOA (aSOA)) does not mix into squalane (a surrogate for hydrophobic primary organic aerosol (POA)) but does mix into SOA derived from α-pinene (biogenic SOA (bSOA) surrogate). For the aSOA/POA, the volatility of either aerosol does not limit gas-phase diffusion, indicating that the two particle populations do not mix simply because they are immiscible. In the aSOA/bSOA system, the presence of toluene-d8-derived SOA molecules in the α-pinene-derived SOA provides evidence that the diffusion coefficient in α-pinene-derived SOA is high enough for mixing on the time scale of 1 min. The observations from all of these mixing experiments are generally invisible to bulk aerosol composition measurements but are made possible with single-particle composition data. PMID:24131283

  16. Reactions and mass spectra of complex particles using Aerosol CIMS

    NASA Astrophysics Data System (ADS)

    Hearn, John D.; Smith, Geoffrey D.

    2006-12-01

    Aerosol chemical ionization mass spectrometry (CIMS) is used both on- and off-line for the analysis of complex laboratory-generated and ambient particles. One of the primary advantages of Aerosol CIMS is the low degree of ion fragmentation, making this technique well suited for investigating the reactivity of complex particles. To demonstrate the usefulness of this "soft" ionization, particles generated from meat cooking were reacted with ozone and the composition was monitored as a function of reaction time. Two distinct kinetic regimes were observed with most of the oleic acid in these particles reacting quickly but with 30% appearing to be trapped in the complex mixture. Additionally, detection limits are measured to be sufficiently low (100-200 ng/m3) to detect some of the more abundant constituents in ambient particles, including sulfate, which is measured in real-time at 1.2 [mu]g/m3. To better characterize complex aerosols from a variety of sources, a novel off-line collection method was also developed in which non-volatile and semi-volatile organics are desorbed from particles and concentrated in a cold U-tube. Desorption from the U-tube followed by analysis with Aerosol CIMS revealed significant amounts of nicotine in cigarette smoke and levoglucosan in oak and pine smoke, suggesting that this may be a useful technique for monitoring particle tracer species. Additionally, secondary organic aerosol formed from the reaction of ozone with R-limonene and volatile organics from orange peel were analyzed off-line showing large molecular weight products (m/z > 300 amu) that may indicate the formation of oligomers. Finally, mass spectra of ambient aerosol collected offline reveal a complex mixture of what appears to be highly processed organics, some of which may contain nitrogen.

  17. Direct gravimetric determination of aerosol mass concentration in central antarctica.

    PubMed

    Annibaldi, Anna; Truzzi, Cristina; Illuminati, Silvia; Scarponi, Giuseppe

    2011-01-01

    In Antarctica, experimental difficulties due to extreme conditions have meant that aerosol mass has rarely been measured directly by gravimetry, and only in coastal areas where concentrations were in the range of 1-7 μg m(-3). The present work reports on a careful differential weighing methodology carried out for the first time on the plateau of central Antarctica (Dome C, East Antarctica). To solve problems of accurate aerosol mass measurements, a climatic room was used for conditioning and weighing filters. Measurements were carried out in long stages of several hours of readings with automatic recording of temperature/humidity and mass. This experimental scheme allowed us to sample from all the measurements (up to 2000) carried out before and after exposure, those which were recorded under the most stable humidity conditions and, even more importantly, as close to each other as possible. The automatic reading of the mass allowed us in any case to obtain hundreds of measurements from which to calculate average values with uncertainties sufficiently low to meet the requirements of the differential weighing procedure (±0.2 mg in filter weighing, between ±7% and ±16% both in aerosol mass and concentration measurements). The results show that the average summer aerosol mass concentration (aerodynamic size ≤10 μm) in central Antarctica is about 0.1 μg m(-3), i.e., about 1/10 of that of coastal Antarctic areas. The concentration increases by about 4-5 times at a site very close to the station. PMID:21141836

  18. A Physically Based Framework for Modelling the Organic Fractionation of Sea Spray Aerosol from Bubble Film Langmuir Equilibria

    SciTech Connect

    Burrows, Susannah M.; Ogunro, O.; Frossard, Amanda; Russell, Lynn M.; Rasch, Philip J.; Elliott, S.

    2014-12-19

    The presence of a large fraction of organic matter in primary sea spray aerosol (SSA) can strongly affect its cloud condensation nuclei activity and interactions with marine clouds. Global climate models require new parameterizations of the SSA composition in order to improve the representation of these processes. Existing proposals for such a parameterization use remotely-sensed chlorophyll-a concentrations as a proxy for the biogenic contribution to the aerosol. However, both observations and theoretical considerations suggest that existing relationships with chlorophyll-a, derived from observations at only a few locations, may not be representative for all ocean regions. We introduce a novel framework for parameterizing the fractionation of marine organic matter into SSA based on a competitive Langmuir adsorption equilibrium at bubble surfaces. Marine organic matter is partitioned into classes with differing molecular weights, surface excesses, and Langmuir adsorption parameters. The classes include a lipid-like mixture associated with labile dissolved organic carbon (DOC), a polysaccharide-like mixture associated primarily with semi-labile DOC, a protein-like mixture with concentrations intermediate between lipids and polysaccharides, a processed mixture associated with recalcitrant surface DOC, and a deep abyssal humic-like mixture. Box model calculations have been performed for several cases of organic adsorption to illustrate the underlying concepts. We then apply the framework to output from a global marine biogeochemistry model, by partitioning total dissolved organic carbon into several classes of macromolecule. Each class is represented by model compounds with physical and chemical properties based on existing laboratory data. This allows us to globally map the predicted organic mass fraction of the nascent submicron sea spray aerosol. Predicted relationships between chlorophyll-\\textit{a} and organic fraction are similar to existing empirical

  19. Relating Aerosol Mass and Optical Depth in the Summertime Continental Boundary Layer

    NASA Astrophysics Data System (ADS)

    Brock, C. A.; Wagner, N.; Middlebrook, A. M.; Attwood, A. R.; Washenfelder, R. A.; Brown, S. S.; McComiskey, A. C.; Gordon, T. D.; Welti, A.; Carlton, A. G.; Murphy, D. M.

    2014-12-01

    Aerosol optical depth (AOD), the column-integrated ambient aerosol light extinction, is determined from satellite and ground-based remote sensing measurements. AOD is the parameter most often used to validate earth system model simulations of aerosol mass. Relating aerosol mass to AOD, however, is problematic due to issues including aerosol water uptake as a function of relative humidity (RH) and the complicated relationship between aerosol physicochemical properties and light extinction. Measurements of aerosol microphysical, chemical, and optical properties help to constrain the relationship between aerosol mass and optical depth because aerosol extinction at ambient RH is a function of the abundance, composition and size distribution of the aerosol. We use vertical profiles of humidity and dry aerosol extinction observed in the southeastern United States (U.S.) to examine the relationship between submicron aerosol mass concentration and extinction at ambient RH. We show that the κ-Köhler parameterization directly, and without additional Mie calculations, describes the change in extinction with varying RH as a function of composition for both aged aerosols typical of the polluted summertime continental boundary layer and the biomass burning aerosols we encountered. We calculate how AOD and the direct radiative effect in the eastern U.S. have likely changed due to trends in aerosol composition in recent decades. We also examine the sensitivity of AOD to the RH profile and to aerosol composition, size distribution and abundance.

  20. Molecular composition of atmospheric aerosols from Halley Bay, Antarctica, using ultra-high resolution mass spectrometry

    NASA Astrophysics Data System (ADS)

    Kourtchev, Ivan; Brough, Neil; Rincon, Angela; Jones, Anna; Kalberer, Markus

    2016-04-01

    Antarctica is one of the few pristine places to study natural processes of atmospheric aerosols and anthropogenic impacts on the clean remote atmosphere. Although stratospheric aerosol in Antarctica has now been explored in some detail because of the ozone depletion phenomenon, tropospheric aerosol particles in Antarctica remain very little studied. The main goal of this work is to identify in detail the organic chemical composition of aerosol from Halley Bay station, which is located on the Brunt Ice Shelf floating on the Weddell Sea in Antarctica. In this study we characterise the molecular composition of aerosols from three seasons (summer, autumn and winter in 2012) using ultra-high resolution mass spectrometry (UHRMS). The technique provides high accuracy and high mass resolving power that allows determining unambiguous number of organic compounds present in complex organic mixtures (Noziere et al., 2015). The molecular composition interpretation was facilitated using visualisation methods (e.g. double bond equivalent, Van Krevelen diagrams, Kendrick mass analysis, and carbon oxidation state), which allowed to identify patterns, such as differences between sampling times and atmospheric processes. The majority of the identified compounds were attributed to nitrogen and sulphur containing species which exhibited very strong seasonal trends. Relatively large fraction (up to 30% of the total number of molecules) of these species contained very low hydrogen to carbon ratios (below 1) indicating that the site is impacted by anthropogenic emissions. Influences of the meteorological parameters and air mass trajectories on the molecular composition are discussed. Nozière et al., The Molecular Identification of Organic Compounds in the Atmosphere: State of the Art and Challenges, Chem. Rev., 115, 3920-3983, 2015.

  1. New characteristics of submicron aerosols and factor analysis of combined organic and inorganic aerosol mass spectra during winter in Beijing

    NASA Astrophysics Data System (ADS)

    Zhang, J. K.; Ji, D. S.; Liu, Z. R.; Hu, B.; Wang, L. L.; Huang, X. J.; Wang, Y. S.

    2015-07-01

    In recent years, an increasing amount of attention has been paid to heavy haze pollution in Beijing, China. In addition to Beijing's population of approximately 20 million and its 5 million vehicles, nearby cities and provinces are host to hundreds of heavily polluting industries. In this study, a comparison between observations in January 2013 and January 2014 showed that non-refractory PM1 (NR-PM1) pollution was weaker in January 2014, which was primarily caused by variations in meteorological conditions. For the first time, positive matrix factorization (PMF) was applied to the merged high-resolution mass spectra of organic and inorganic aerosols from aerosol mass spectrometer measurements in Beijing, and the sources and evolution of NR-PM1 in January 2014 were investigated. The two factors, NO3-OA1 and NO3-OA2, were primarily composed of ammonium nitrate, and each showed a different degree of oxidation and diurnal variation. The organic fraction of SO4-OA showed the highest degree of oxidation of all PMF factors. The hydrocarbon-like organic aerosol (OA) and cooking OA factors contained negligible amounts of inorganic species. The coal combustion OA factor contained a high contribution from chloride in its mass spectrum. The NR-PM1 composition showed significant variations in January 2014, in which the contribution of nitrate clearly increased during heavy pollution events. The most effective way to control fine particle pollution in Beijing is through joint prevention and control measures at the regional level, rather than a focus on an individual city, especially for severe haze events.

  2. The Aerosol Research and Inhalation Epidemiology Study (ARIES): PM2.5 mass and aerosol component concentrations and sampler intercomparisons.

    PubMed

    Van Loy, M; Bahadori, T; Wyzga, R; Hartsell, B; Edgerton, E

    2000-08-01

    The Aerosol Research and Inhalation Epidemiology Study (ARIES) was designed to provide high-quality measurements of PM2.5, its components, and co-varying pollutants for an air pollution epidemiology study in Atlanta, GA. Air pollution epidemiology studies have typically relied on available data on particle mass often collected using filter-based methods. Filter-based PM2.5 sampling is susceptible to both positive and negative errors in the measurement of aerosol mass and particle-phase component concentrations in the undisturbed atmosphere. These biases are introduced by collection of gas-phase aerosol components on the filter media or by volatilization of particle phase components from collected particles. As part of the ARIES, we collected daily 24-hr PM2.5 mass and speciation samples and continuous PM2.5 data at a mixed residential-light industrial site in Atlanta. These data facilitate analysis of the effects of a wide variety of factors on sampler performance. We assess the relative importance of PM2.5 components and consider associations and potential mechanistic linkages of PM2.5 mass concentrations with several PM2.5 components. For the 12 months of validated data collected to date (August 1, 1998-July 31, 1999), the monthly average Federal Reference Method (FRM) PM2.5 mass always exceeded the proposed annual average standard (12-month average = 20.3 +/- 9.5 micrograms/m3). The particulate SO4(2-) fraction (as (NH4)2SO4) was largest in the summer and exceeded 50% of the FRM mass. The contribution of (NH4)2SO4 to FRM PM2.5 mass dropped to less than 30% in winter. Particulate NO3- collected on a denuded nylon filter averaged 1.1 +/- 0.9 micrograms/m3. Particle-phase organic compounds (as organic carbon x 1.4) measured on a denuded quartz filter sampler averaged 6.4 +/- 3.1 micrograms/m3 (32% of FRM PM2.5 mass) with less seasonal variability than SO4(2-). PMID:11002607

  3. Atmospheric pressure flow reactor / aerosol mass spectrometer studies of tropospheric aerosol nucleat and growth kinetics. Final report, June, 2001

    SciTech Connect

    Worsnop, Douglas R.

    2001-06-01

    The objective of this program was to determine the mechanisms and rates of growth and transformation and growth processes that control secondary aerosol particles in both the clear and polluted troposphere. The experimental plan coupled an aerosol mass spectrometer (AMS) with a chemical ionization mass spectrometer to provide simultaneous measurement of condensed and particle phases. The first task investigated the kinetics of tropospheric particle growth and transformation by measuring vapor accretion to particles (uptake coefficients, including mass accommodation coefficients and heterogeneous reaction rate coefficients). Other work initiated investigation of aerosol nucleation processes by monitoring the appearance of submicron particles with the AMS as a function of precursor gas concentrations. Three projects were investigated during the program: (1) Ozonolysis of oleic acid aerosols as model of chemical reactivity of secondary organic aerosol; (2) Activation of soot particles by measurement deliquescence in the presence of sulfuric acid and water vapor; (3) Controlled nucleation and growth of sulfuric acid aerosols.

  4. Modeling the organic aerosol fraction within the Mexico City basin during the MILAGRO field experiment

    NASA Astrophysics Data System (ADS)

    Hodzic, A.; Jimenez, J. L.; Madronich, S.; Aiken, A. C.; Bessagnet, B.; Fast, J.; Lamarque, J. F.; Onasch, T. B.; Roux, G.; Ulbrich, I. M.

    2009-04-01

    The meso-scale chemistry-transport model CHIMERE is used to asses our understanding of major sources and formation processes leading to a fairly abundant fraction of organic aerosols (OA, including primary OA (POA) and secondary OA (SOA)) observed in Mexico City during the MILAGRO field project (March 2006). Chemical analysis of submicron aerosols from aerosol mass spectrometers (AMS) indicate that carbonaceous particles found in the Mexico City basin have a large fraction of oxygenated organic species (OOA) which show strong correspondence with SOA, and that their production actively continues downwind of the city. The SOA formation is modeled according to the first-generation oxidation of anthropogenic (i.e. aromatics, alkanes) and biogenic (i.e. monoterpenes and isoprene) precursors and their partitioning into both organic and aqueous phases. The near-surface model evaluation shows that predicted OA correlates reasonably well with measurements during the campaign, however it remains a factor of 2-3 lower than the measured TOA. One of the reasons for this large gap is the inability of the model to simulate TOA peaks associated with the biomass burning events suggesting that near-city fires are not correctly represented in the emissions inventory (most likely too small to be detected by satellites). Fairly good agreement is found between observed and predicted POA within the city indicating that primary emissions are reasonable. Consistent with previous studies in Mexico City, large discrepancies are found for SOA species characterized by a factor of 5-10 model underestimate. When only anthropogenic SOA precursors were considered, the model was able to reproduce the sharp increase in SOA concentrations during the late morning at both urban and near-urban locations. However, predicted SOA concentrations were unrealistically low when photochemistry was not active, especially overnight. These discrepancies were not significantly reduced when greatly enhanced

  5. Mass size distributions of elemental aerosols in industrial area

    PubMed Central

    Moustafa, Mona; Mohamed, Amer; Ahmed, Abdel-Rahman; Nazmy, Hyam

    2014-01-01

    Outdoor aerosol particles were characterized in industrial area of Samalut city (El-minia/Egypt) using low pressure Berner cascade impactor as an aerosol sampler. The impactor operates at 1.7 m3/h flow rate. Seven elements were investigated including Ca, Ba, Fe, K, Cu, Mn and Pb using atomic absorption technique. The mean mass concentrations of the elements ranged from 0.42 ng/m3 (for Ba) to 89.62 ng/m3 (for Fe). The mass size distributions of the investigated elements were bi-modal log normal distribution corresponding to the accumulation and coarse modes. The enrichment factors of elements indicate that Ca, Ba, Fe, K, Cu and Mn are mainly emitted into the atmosphere from soil sources while Pb is mostly due to anthropogenic sources. PMID:26644919

  6. Seasonal differences of urban organic aerosol composition - an ultra-high resolution mass spectrometry study

    NASA Astrophysics Data System (ADS)

    Rincon, A. G.; Calvo, A. I.; Dietzel, M.; Kalberer, M.

    2012-04-01

    The understanding of the chemical composition of atmospheric aerosols, their properties and reactivity are important for assessing aerosol effects upon both global climate change and human health. The composition of organic aerosols is poorly understood mainly due to their highly complex chemical composition with several thousand compounds. In the present study the water-soluble organic fraction of ambient particles collected at an urban site in Cambridge, UK, during different seasons were analysed with ultra-high resolution mass spectrometry. For several thousand peaks in the mass specta (between 3000-6000) an elemental composition could be assigned and summer samples generally contained more components than winter samples. Up to 80% of the peaks in the mass spectra contain nitrogen and/or sulphur functional groups and only about 20% of the compounds contain only C, H and O atoms. In summer the fraction of compounds with oxidized nitrogen and sulphur groups increases compared to winter indicating a photo-chemical formation route of these multifunctional compounds. In addition to oxidized nitrogen compounds a large number of highly unsaturated reduced nitrogen-containing compounds were detected, corresponding likely to cyclic amines. A significant number of oxidized PAHs have been detected in summer samples, which were not present in winter, indicating again photo-chemical aging processes. Both, amines and long-chain aliphatic acids (also frequently observed in these urban samples) are likely signatures of biomass burning and primary biological sources. Potential biomass burning markers are discussed. Particle-phase oligomerisation reactions have only been observed to a very limited degree. Compounds larger than m/z 350 almost exclusively contained N and/or S functional groups indicating that the high molecular weight compounds in these organic aerosol extracts might be mainly due to particle-phase heterogeneous reactions of organic compounds with inorganic

  7. Analysis of Organic Anionic Surfactants in Fine and Coarse Fractions of Freshly Emitted Sea Spray Aerosol.

    PubMed

    Cochran, Richard E; Laskina, Olga; Jayarathne, Thilina; Laskin, Alexander; Laskin, Julia; Lin, Peng; Sultana, Camille; Lee, Christopher; Moore, Kathryn A; Cappa, Christopher D; Bertram, Timothy H; Prather, Kimberly A; Grassian, Vicki H; Stone, Elizabeth A

    2016-03-01

    The inclusion of organic compounds in freshly emitted sea spray aerosol (SSA) has been shown to be size-dependent, with an increasing organic fraction in smaller particles. Here we have used electrospray ionization-high resolution mass spectrometry in negative ion mode to identify organic compounds in nascent sea spray collected throughout a 25 day mesocosm experiment. Over 280 organic compounds from ten major homologous series were tentatively identified, including saturated (C8-C24) and unsaturated (C12-C22) fatty acids, fatty acid derivatives (including saturated oxo-fatty acids (C5-C18) and saturated hydroxy-fatty acids (C5-C18), organosulfates (C2-C7, C12-C17) and sulfonates (C16-C22). During the mesocosm, the distributions of molecules within some homologous series responded to variations among the levels of phytoplankton and bacteria in the seawater. The average molecular weight and carbon preference index of saturated fatty acids significantly decreased within fine SSA during the progression of the mesocosm, which was not observed in coarse SSA, sea-surface microlayer or in fresh seawater. This study helps to define the molecular composition of nascent SSA and biological processes in the ocean relate to SSA composition. PMID:26828238

  8. Laboratory and field measurements of organic aerosols with the photoionization aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Dreyfus, Matthew A.

    Analytical methods developed to sample and characterize ambient organic aerosols often face the trade-off between long sampling times and the loss of detailed information regarding specific chemical species present. The soft, universal ionization scheme of the Photoionization Aerosol Mass Spectrometer (PIAMS) allows for identification of various chemical compounds by a signature ion, often the molecular ion. The goal of this thesis work is to apply PIAMS to both laboratory and field experiments to answer questions regarding the formation, composition, and behavior of organic aerosols. To achieve this goal, a variety of hardware and software upgrades were administered to PIAMS to optimize the instrument. Data collection and processing software were either refined or built from the ground up to simplify difficult or monotonous tasks. Additional components were added to PIAMS with the intent to automate the instrument, enhance the results, and make the instrument more rugged and user-friendly. These changes, combined with the application of an external particle concentration system (mini-Versatile Aerosol Concentration Enrichment System, m-VACES), allowed PIAMS to be suitable for field measurements of organic aerosols. Two such field campaigns were completed, both at the State of Delaware Air Quality Monitoring Site in Wilmington, Delaware: a one week period in June, 2006, and an 18 day period in October and November of 2007. A sampling method developed was capable of collecting sufficient ambient organic aerosol and analyzing it with a time resolution of 3.5 minutes. Because of this method, short term concentration changes of individual species can be tracked. Combined with meteorological data, the behavior of these species can be analyzed as a function of time or wind direction. Many compounds are found at enhanced levels during the evening/night-time hours; potentially due to the combined effects of temperature inversion, and fresh emissions in a cooler environment

  9. THE UNIVERSAL GAS MASS FRACTION IN CLUSTERS OF GALAXIES

    SciTech Connect

    David, Laurence P.; Jones, Christine; Forman, William

    2012-04-01

    We obtained a deep 150 ks Chandra observation of the optically selected cluster of galaxies, RCS 2318+0034, to investigate the gas mass fraction in this system. Combining our deep Chandra observation with an archival 50 ks observation, we derive gas mass fractions of f{sub gas} = 0.06 {+-} .02 and 0.10 {+-} .02 within r{sub 2500} and r{sub 500}, respectively. The gas mass fraction in RCS 2318+0034 within r{sub 500} is typical of X-ray-selected clusters. Further study shows that the large-scale properties of RCS 2318+0034, including the relations between gas mass, X-ray luminosity, and gas temperature, are also consistent with the observed correlations of X-ray-selected clusters. However, the gas mass fraction within r{sub 2500} is less than most X-ray-selected clusters, as previously reported. The deep Chandra image of RCS 2318+0034 shows that this system is currently undergoing a major merger which may have an impact on the inferred gas mass fraction within r{sub 2500}.

  10. Combined volatility and mass spectrometric measurements of biogenic secondary organic aerosol

    NASA Astrophysics Data System (ADS)

    Emanuelsson, E.; Buchholz, A.; Hallquist, M.; Kiendler-Scharr, A.; Mentel, T.; Spindler, C.

    2009-04-01

    The volatility of secondary organic aerosol (SOA) from the oxidation of mixtures of biogenic Volatile Organic Compounds (VOC) has been investigated in the SAPHIR facility in Forschungszentrum Jülich, Germany, by using a Volatility Tandem Differential Mobility Analyser (VTDMA). The standard VTDMA setup comprises three main parts: 1) An initial DMA, where a nearly monodisperse size fraction of the aerosol particles is selected (typically 100 or 150 nm), 2) the oven unit, i.e. four ovens in parallel where each oven includes a heating and adsorption section where the evaporation and adsorption of the volatile fraction occurs and 3) a final SMPS (Scanning Mobility Particle Sizer) system where the residual particle number distribution is measured. For this measurement campaign the set-up also contained a Quadrupole Aerosol Mass Spectrometer (Aerodyne QAMS). The temperature of the ovens can be varied between 298 and well above 573 K. In parallel to the final SMPS the AMS was used for chemical composition and density measurements. When the system was dedicated for AMS measurements the initial DMA was bypassed to improve the aerosol concentration. However, the produced SOA has a narrow size distribution still making it possible to follow small changes in the aerosol peak diameter. A general feature of the thermo-denuder system is that a less volatile SOA gives a larger residual particle size distribution compared to more volatile SOA. The experiments conducted were based on photochemical oxidation of selected terpene mixtures. A reference boreal mixture of terpenes, consisting of α-pinene, β-pinene, limonene, ^-3-carene, and ocimene was used as base case. Secondary organic aerosol was formed from the precursor compounds by reaction with O3/H2O/OH in SAPHIR on the first day. The particles were kept in the chamber for up to two further days and were exposed to natural sunlight and OH radicals to initiate close to natural chemical ageing. The VTDMA results show that SOA

  11. THE BINARY FRACTION OF LOW-MASS WHITE DWARFS

    SciTech Connect

    Brown, Justin M.; Kilic, Mukremin; Brown, Warren R.; Kenyon, Scott J.

    2011-04-01

    We describe spectroscopic observations of 21 low-mass ({<=}0.45 M{sub sun}) white dwarfs (WDs) from the Palomar-Green survey obtained over four years. We use both radial velocities and infrared photometry to identify binary systems, and find that the fraction of single, low-mass WDs is {<=}30%. We discuss the potential formation channels for these single stars including binary mergers of lower-mass objects. However, binary mergers are not likely to explain the observed number of single low-mass WDs. Thus, additional formation channels, such as enhanced mass loss due to winds or interactions with substellar companions, are likely.

  12. Experimental investigation of mass-dependent and mass-independent fractionation of mercury isotopes

    NASA Astrophysics Data System (ADS)

    Bergquist, B. A.; Blum, J. D.; Marcus, J. W.; Biswas, A.

    2006-12-01

    Mercury is a globally distributed and highly toxic pollutant, the mobility and bioaccumulation of which is highly dependent on its redox cycling. With seven isotopes (including two odd-mass isotopes) and a relative mass difference of 4%, stable isotope fractionation of Hg could be a powerful tool to track and understand Hg cycling in the environment. Ongoing studies of natural mercury isotope variations in ore deposits, hydrothermal fluids, sediments, soils, fish tissues and bacterial cultures have documented a measurable range in Hg isotopes of up to ~5‰ in the ^{202}Hg/^{198}Hg ratio with most samples displaying mass-dependent fractionation. A small, but growing, body of data also suggests that natural samples display mass-independent fractionation of Hg isotopes. In this study, we explore mechanisms that lead to both mass- dependent and mass-independent fractionation of Hg isotopes. Isotope ratios were measured by continuous- flow cold-vapor generation coupled to MC-ICPMS with an external precision of ±0.1‰ (2SD). We observe three distinct types of isotope fractionation for Hg: (1) mass-dependent fractionation, (2) mass- independent fractionation of odd isotopes concurrent with mass-dependent fractionation of even isotopes, and (3) mass-independent fractionation of all Hg isotopes. Reduction of Hg species to Hg(0) vapor is an important mechanism for removal of Hg from aqueous systems into the atmosphere. Reduction of Hg occurs through numerous pathways including photoreduction, abiotic organic reduction, and biological reduction. We find that photoreduction of Hg(II) by natural sunlight leads to mass-independent fractionation of the odd isotopes (^{201}Hg, ^{199}Hg) with several permil deviations from predicted mass dependence, and mass- dependent fractionation of the even isotopes. In contrast, both biological reduction (Kritee et al., 2006) and dark abiotic organically mediated reduction follow mass-dependent fractionation of even and odd isotopes

  13. Ambient Aerosol in Southeast Asia: High Resolution Aerosol Mass Spectrometer Measurements Over Oil Palm (Elaeis guineensis)

    NASA Astrophysics Data System (ADS)

    Phillips, G.; Dimarco, C.; Misztal, P.; Nemitz, E.; Farmer, D.; Kimmel, J.; Jimenez, J.

    2008-12-01

    The emission of organic compounds in the troposphere is important factor in the formation of secondary organic aerosol (SOA). A very large proportion of organic material emitted globally is estimated to arise from biogenic sources, with almost half coming from tropical and sub-tropical forests. Preliminary analyses of leave cuvette emission studies suggest that oil palm (Elaeis guineensis) is a significantly larger source of isoprene than tropical forest. Much larger sources of isoprene over oil palm allied with a larger anthropogenic component of local emissions contrast greatly with the remote tropical forest environment and therefore the character of SOA formed may differ significantly. These issues, allied with the high price of palm oil on international markets leading to increased use of land for oil palm production, could give rise to rapidly changing chemical and aerosol regimes in the tropics. It is therefore important to understand the current emissions and composition of organic aerosol over all important land-uses in the tropical environment. This in turn will lead to a greater understanding of the present, and to an improvement in predictive capacity for the future system. To help address these issues, a high resolution time of flight aerosol mass spectrometer (HR-ToF-AMS) was deployed in the Sabahmas (PPB OIL) oil palm plantation near Lahad Datu, in Eastern Sabah, as part of the field component of the Aerosol Coupling in the Earth System (ACES) project, part of the UK NERC APPRAISE program. This project was allied closely with measurements made of similar chemical species and aerosol components at a forest site in the Danum Valley as part of the UK Oxidant and Particle Photochemical Processes above a Southeast Asian tropical rainforest (OP3) project. Measurements of submicron non- refractory aerosol composition are presented along with some preliminary analysis of chemically resolved aerosol fluxes made with a new eddy covariance system, based on the

  14. Detection of biological particles in ambient air using bio-aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    McJimpsey, Erica L.; Steele, Paul T.; Coffee, Keith R.; Fergenson, David P.; Riot, Vincent J.; Woods, Bruce W.; Gard, Eric E.; Frank, Matthias; Tobias, Herbert J.; Lebrilla, Carlito

    2006-05-01

    The Bio-Aerosol Mass Spectrometry (BAMS) system is an instrument used for the real time detection and identification of biological aerosols. Particles are drawn from the atmosphere directly into vacuum and tracked as they scatter light from several continuous wave lasers. After tracking, the fluorescence of individual particles is excited by a pulsed 266nm or 355nm laser. Molecules from those particles with appropriate fluorescence properties are subsequently desorbed and ionized using a pulsed 266nm laser. Resulting ions are analyzed in a dual polarity mass spectrometer. During two field deployments at the San Francisco International Airport, millions of ambient particles were analyzed and a small but significant fraction were found to have fluorescent properties similar to Bacillus spores and vegetative cells. Further separation of non-biological background particles from potential biological particles was accomplished using laser desorption/ionization mass spectrometry. This has been shown to enable some level of species differentiation in specific cases, but the creation and observation of higher mass ions is needed to enable a higher level of specificity across more species. A soft ionization technique, matrix-assisted laser desorption/ionization (MALDI) is being investigated for this purpose. MALDI is particularly well suited for mass analysis of biomolecules since it allows for the generation of molecular ions from large mass compounds that would fragment under normal irradiation. Some of the initial results from a modified BAMS system utilizing this technique are described.

  15. Detection of biological particles in ambient air using Bio-Aerosol Mass Spectrometry

    SciTech Connect

    McJimpsey, E L; Steele, P T; Coffee, K R; Fergenson, D P; Riot, V J; Woods, B W; Gard, E E; Frank, M; Tobias, H J; Lebrilla, C

    2006-03-16

    The Bio-Aerosol Mass Spectrometry (BAMS) system is an instrument used for the real time detection and identification of biological aerosols. Particles are drawn from the atmosphere directly into vacuum and tracked as they scatter light from several continuous wave lasers. After tracking, the fluorescence of individual particles is excited by a pulsed 266nm or 355nm laser. Molecules from those particles with appropriate fluorescence properties are subsequently desorbed and ionized using a pulsed 266nm laser. Resulting ions are analyzed in a dual polarity mass spectrometer. During two field deployments at the San Francisco International Airport, millions of ambient particles were analyzed and a small but significant fraction were found to have fluorescent properties similar to Bacillus spores and vegetative cells. Further separation of non-biological background particles from potential biological particles was accomplished using laser desorption/ionization mass spectrometry. This has been shown to enable some level of species differentiation in specific cases, but the creation and observation of higher mass ions is needed to enable a higher level of specificity across more species. A soft ionization technique, matrix-assisted laser desorption/ionization (MALDI) is being investigated for this purpose. MALDI is particularly well suited for mass analysis of biomolecules since it allows for the generation of molecular ions from large mass compounds that would fragment under normal irradiation. Some of the initial results from a modified BAMS system utilizing this technique are described.

  16. Contrasting trends of mass and optical properties of aerosols over the Northern Hemisphere from 1992 to 2011

    NASA Astrophysics Data System (ADS)

    Wang, K.; Dickinson, R. E.; Su, L.; Trenberth, K. E.

    2012-07-01

    Atmospheric aerosols impact both human health and climate. PMX is the mass concentration of aerosol particles that have aerodynamic diameters less than X μm, PM10 was initially selected to measure the environmental impact of aerosols. Recently, it was realized that fine particles are more hazardous than larger ones and should be measured. Consequently, observational data for PM2.5 have been obtained but only for a much shorter period than that of PM10. Optical extinction of aerosols, the inverse of meteorological visibility, is sensitive to particles less than 1.0 μm. These fine particles only account for a small part of total mass of aerosols although they are very efficient in light extinction. Comparisons are made between PM10 and PM2.5 over the period when the latter is available and with visibility data for a longer period. PM10 has decreased by 44% in Europe from 1992 to 2009, 33% in the US from 1993 to 2010, 10% in Canada from 1994 to 2009, and 26% in China from 2000 to 2010. However, in contrast, aerosol optical extinction increased 7% in the US, 10% in Canada, and 18% in China during the above study periods. The reduction of optical extinction over Europe of 5% is also much less than the 44% reduction in PM10. Over its short period of record PM2.5 decreased less than PM10. Hence, PM10 is neither a good measure of changes in smaller particles or of their long-term trends, a result that has important implications for both climate impact and human health effects. The increased fraction of anthropogenic aerosol emission, such as vehicle exhaust, to total atmospheric aerosols partly explains this contrasting trend of optical and mass properties of aerosols.

  17. Contrasting trends of mass and optical properties of aerosols over the Northern Hemisphere from 1992 to 2011

    NASA Astrophysics Data System (ADS)

    Wang, K. C.; Dickinson, R. E.; Su, L.; Trenberth, K. E.

    2012-10-01

    Atmospheric aerosols affect both human health and climate. PMX is the mass concentration of aerosol particles that have aerodynamic diameters less than X μm, PM10 was initially selected to measure the environmental impact of aerosols. Recently, it was realized that fine particles are more hazardous than larger ones and should be measured. Consequently, observational data for PM2.5 have been obtained but only for a much shorter period than that of PM10. Optical extinction of aerosols, the inverse of meteorological visibility, is sensitive to particles less than 1.0 μm. These fine particles only account for a small part of total mass of aerosols although they are very efficient in light extinction. Comparisons are made between PM10 and PM2.5 over the period when the latter is available and with visibility data for a longer period. PM10 has decreased by 44% in Europe from 1992 to 2009, 33% in the US from 1993 to 2010, 10% in Canada from 1994 to 2009, and 26% in China from 2000 to 2011. However, in contrast, aerosol optical extinction has increased 7% in the US, 10% in Canada, and 18% in China during the above study periods. The reduction of optical extinction over Europe of 5% is also much less than the 44% reduction in PM10. Over its short period of record PM2.5 decreased less than PM10. Hence, PM10 is neither a good measure of changes in smaller particles nor of their long-term trends, a result that has important implications for both climate impact and human health effects. The increased fraction of anthropogenic aerosol emission, such as from vehicle exhaust, to total atmospheric aerosols partly explains this contrasting trend of optical and mass properties of aerosols.

  18. A new method for estimating aerosol mass flux in the urban surface layer using LAS technology

    NASA Astrophysics Data System (ADS)

    Yuan, Renmin; Luo, Tao; Sun, Jianning; Liu, Hao; Fu, Yunfei; Wang, Zhien

    2016-04-01

    Atmospheric aerosol greatly influences human health and the natural environment, as well as the weather and climate system. Therefore, atmospheric aerosol has attracted significant attention from society. Despite consistent research efforts, there are still uncertainties in understanding its effects due to poor knowledge about aerosol vertical transport caused by the limited measurement capabilities of aerosol mass vertical transport flux. In this paper, a new method for measuring atmospheric aerosol vertical transport flux is developed based on the similarity theory of surface layer, the theory of light propagation in a turbulent atmosphere, and the observations and studies of the atmospheric equivalent refractive index (AERI). The results show that aerosol mass flux can be linked to the real and imaginary parts of the atmospheric equivalent refractive index structure parameter (AERISP) and the ratio of aerosol mass concentration to the imaginary part of the AERI. The real and imaginary parts of the AERISP can be measured based on the light-propagation theory. The ratio of the aerosol mass concentration to the imaginary part of the AERI can be measured based on the measurements of aerosol mass concentration and visibility. The observational results show that aerosol vertical transport flux varies diurnally and is related to the aerosol spatial distribution. The maximum aerosol flux during the experimental period in Hefei City was 0.017 mg m-2 s-1, and the mean value was 0.004 mg m-2 s-1. The new method offers an effective way to study aerosol vertical transport in complex environments.

  19. Identification of characteristic mass spectrometric markers for primary biological aerosol particles and comparison with field data from submicron pristine aerosol particles

    NASA Astrophysics Data System (ADS)

    Freutel, F.; Schneider, J.; Zorn, S. R.; Drewnick, F.; Borrmann, S.; Hoffmann, T.; Martin, S. T.

    2009-04-01

    The contribution of primary biological aerosol (PBA) to the total aerosol particle concentration is estimated to range between 25 and 80%, depending on location and season. Especially in the tropical rain forest it is expected that PBA is a major source of particles in the supermicron range, and is also an important fraction of the submicron aerosol. PBA particles like plant fragments, pollen, spores, fungi, viruses etc. contain chemical compounds as proteins, sugars, amino acids, chlorophyll, and cellular material as cellulose. For this reason we have performed mass spectrometric laboratory measurements (Aerodyne C-ToF and W-ToF AMS, single particle laser ablation instrument SPLAT) on pure submicron aerosol particles containing typical PBA compounds in order to identify typical mass spectral patterns of these compounds and to explain the observed fragmentation patterns on the basis of molecular structures. These laboratory data were compared to submicron particle mass spectra obtained during AMAZE-08 (Amazonian Aerosol CharacteriZation Experiment, Brazil, February/March 2008). The results indicate that characteristic m/z ratios for carbohydrates (e.g., glucose, saccharose, levoglucosan, mannitol) can be identified, for example m/z = 60(C2H4O2+) or m/z = 61(C2H5O2+). Certain characteristic peaks for amino acids were also identified in the laboratory experiments. In the field data from AMAZE-08, these characteristic peaks for carbohydrates and amino acids were found, and their contribution to the total organic mass was estimated to about 5%. Fragment ions from peptides and small proteins were also identified in laboratory experiments. Larger proteins, however, seem to become oxidized to CO2+ to a large extend in the vaporizing process of the AMS. Thus, detection of proteins in atmospheric aerosol particles with the AMS appears to be difficult.

  20. Improving Calculation Accuracies of Accumulation-Mode Fractions Based on Spectral of Aerosol Optical Depths

    NASA Astrophysics Data System (ADS)

    Ying, Zhang; Zhengqiang, Li; Yan, Wang

    2014-03-01

    Anthropogenic aerosols are released into the atmosphere, which cause scattering and absorption of incoming solar radiation, thus exerting a direct radiative forcing on the climate system. Anthropogenic Aerosol Optical Depth (AOD) calculations are important in the research of climate changes. Accumulation-Mode Fractions (AMFs) as an anthropogenic aerosol parameter, which are the fractions of AODs between the particulates with diameters smaller than 1μm and total particulates, could be calculated by AOD spectral deconvolution algorithm, and then the anthropogenic AODs are obtained using AMFs. In this study, we present a parameterization method coupled with an AOD spectral deconvolution algorithm to calculate AMFs in Beijing over 2011. All of data are derived from AErosol RObotic NETwork (AERONET) website. The parameterization method is used to improve the accuracies of AMFs compared with constant truncation radius method. We find a good correlation using parameterization method with the square relation coefficient of 0.96, and mean deviation of AMFs is 0.028. The parameterization method could also effectively solve AMF underestimate in winter. It is suggested that the variations of Angstrom indexes in coarse mode have significant impacts on AMF inversions.

  1. Aqueous-phase photooxidation of levoglucosan - a mechanistic study using aerosol time-of-flight chemical ionization mass spectrometry (Aerosol ToF-CIMS)

    NASA Astrophysics Data System (ADS)

    Zhao, R.; Mungall, E. L.; Lee, A. K. Y.; Aljawhary, D.; Abbatt, J. P. D.

    2014-09-01

    Levoglucosan (LG) is a widely employed tracer for biomass burning (BB). Recent studies have shown that LG can react rapidly with hydroxyl (OH) radicals in the aqueous phase despite many mass balance receptor models assuming it to be inert during atmospheric transport. In the current study, aqueous-phase photooxidation of LG by OH radicals was performed in the laboratory. The reaction kinetics and products were monitored by aerosol time-of-flight chemical ionization mass spectrometry (Aerosol ToF-CIMS). Approximately 50 reaction products were detected by the Aerosol ToF-CIMS during the photooxidation experiments, representing one of the most detailed product studies yet performed. By following the evolution of mass defects of product peaks, unique trends of adding oxygen (+O) and removing hydrogen (-2H) were observed among the products detected, providing useful information for determining potential reaction mechanisms and sequences. Additionally, bond-scission reactions take place, leading to reaction intermediates with lower carbon numbers. We introduce a data analysis framework where the average oxidation state (OSc) is plotted against a novel molecular property: double-bond-equivalence-to-carbon ratio (DBE/#C). The trajectory of LG photooxidation on this plot suggests formation of polycarbonyl intermediates and their subsequent conversion to carboxylic acids as a general reaction trend. We also determined the rate constant of LG with OH radicals at room temperature to be 1.08 ± 0.16 × 109 M-1 s-1. By coupling an aerosol mass spectrometer (AMS) to the system, we observed a rapid decay of the mass fraction of organic signals at mass-to-charge ratio 60 (f60), corresponding closely to the LG decay monitored by the Aerosol ToF-CIMS. The trajectory of LG photooxidation on a f44-f60 correlation plot matched closely to literature field measurement data. This implies that aqueous-phase photooxidation might be partially contributing to aging of BB particles in the

  2. Aqueous-phase photooxidation of levoglucosan - a mechanistic study using Aerosol Time of Flight Chemical Ionization Mass Spectrometry (Aerosol-ToF-CIMS)

    NASA Astrophysics Data System (ADS)

    Zhao, R.; Mungall, E. L.; Lee, A. K. Y.; Aljawhary, D.; Abbatt, J. P. D.

    2014-04-01

    Levoglucosan (LG) is a widely employed tracer for biomass burning (BB). Recent studies have shown that LG can react rapidly with hydroxyl (OH) radicals in the aqueous phase, despite many mass balance receptor models assuming it to be inert during atmospheric transport. In the current study, aqueous-phase photooxidation of LG by OH radicals was performed in the laboratory. The reaction kinetics and products were monitored by Aerosol Time of Flight Chemical Ionization Mass Spectrometry (Aerosol-ToF-CIMS). Approximately 50 reaction products were detected by the Aerosol-ToF-CIMS during the photooxidation experiments, representing one of the most detailed product studies yet performed. By following the evolution of mass defects of product peaks, unique trends of adding oxygen (+O) and removing hydrogen (-2H) were observed among the products detected, providing useful information to determine potential reaction mechanisms and sequences. As well, bond scission reactions take place, leading to reaction intermediates with lower carbon numbers. We introduce a data analysis framework where the average oxidation state (OSc) is plotted against a novel molecular property: double bond equivalence to carbon ratio (DBE / #C). The trajectory of LG photooxidation on this plot suggests formation of poly-carbonyl intermediates and their subsequent conversion to carboxylic acids as a general reaction trend. We also determined the rate constant of LG with OH radicals at room temperature to be 1.08 ± 0.16 × 109 M-1 s-1. By coupling an Aerosol Mass Spectrometer (AMS) to the system, we observed a rapid decay of the mass fraction of organic signals at mass-to-charge ratio 60 (f60), corresponding closely to the LG decay monitored by the Aerosol-ToF-CIMS. The trajectory of LG photooxidation on a f44-f60 correlation plot matched closely to literature field measurement data. This implies that aqueous-phase photooxidation might be partially contributing to aging of BB particles in the ambient

  3. Aerosol chemical elemental mass concentration at lower free troposphere

    NASA Astrophysics Data System (ADS)

    do Carmo Freitas, Maria; Dionísio, Isabel; Fialho, Paulo; Barata, Filipe

    2007-08-01

    This paper shows the use of Instrumental neutron activation analysis (INAA) technique to determine elemental masses collected by a seven-wavelength Aethalometer instrument at the summit of Pico mountain in the Azorean archipelago, situated in the Central North Atlantic Ocean. Each sample corresponds to air particulate matter measured continuously for periods of approximately 24 h taken from 14th July 2001 through 14th July 2002. The statistical analysis of the coefficients of correlation between all the elements identified, permitted to establish six groups that could potentially be associated with the type of source responsible for the aerosol sampled in the lower free troposphere at the Azorean archipelago. Calculation of the synoptic back trajectories helped to corroborate the use of the iron/cesium relation as a tracer for the Saharan dust aerosol. It was demonstrated that INAA constituted an important tool to identify these events.

  4. The link between organic aerosol mass loading and degree of oxygenation: an α-pinene photooxidation study

    NASA Astrophysics Data System (ADS)

    Pfaffenberger, L.; Barmet, P.; Slowik, J. G.; Praplan, A. P.; Dommen, J.; Prévôt, A. S. H.; Baltensperger, U.

    2013-07-01

    A series of smog chamber (SC) experiments was conducted to identify factors responsible for the discrepancy between ambient and SC aerosol degree of oxygenation. An Aerodyne high-resolution time-of-flight aerosol mass spectrometer is used to compare mass spectra from α-pinene photooxidation with ambient aerosol. Composition is compared in terms of the fraction of particulate CO2+, a surrogate for carboxylic acids, vs. the fraction of C2H3O+, a surrogate for aldehydes, alcohols and ketones, as well as in the Van Krevelen space, where the evolution of the atomic hydrogen-to-carbon ratio (H : C) vs. the atomic oxygen-to-carbon ratio (O : C) is investigated. Low (near-ambient) organic mass concentrations were found to be necessary to obtain oxygenation levels similar to those of low-volatility oxygenated organic aerosol (LV-OOA) commonly identified in ambient measurements. The effects of organic mass loading and OH (hydroxyl radical) exposure were decoupled by inter-experiment comparisons at the same integrated OH concentration. An OH exposure between 3 and 25 × 107 cm-3 h is needed to increase O : C by 0.05 during aerosol aging. For the first time, LV-OOA-like aerosol from the abundant biogenic precursor α-pinene was produced in a smog chamber by oxidation at typical atmospheric OH concentrations. Significant correlation between measured secondary organic aerosol (SOA) and reference LV-OOA mass spectra is shown by Pearson's R2 values larger than 0.90 for experiments with low organic mass concentrations between 1.2 and 18 μg m-3 at an OH exposure of 4 × 107 cm-3 h, corresponding to about two days of oxidation time in the atmosphere, based on a global mean OH concentration of ~ 1 × 106 cm-3. α-Pinene SOA is more oxygenated at low organic mass loadings. Because the degree of oxygenation influences the chemical, volatility and hygroscopic properties of ambient aerosol, smog chamber studies must be performed at near-ambient concentrations to accurately simulate

  5. Changes in organic aerosol composition with aging inferred from aerosol mass spectra

    NASA Astrophysics Data System (ADS)

    Ng, N. L.; Canagaratna, M. R.; Jimenez, J. L.; Chhabra, P. S.; Seinfeld, J. H.; Worsnop, D. R.

    2011-03-01

    Organic aerosols (OA) can be separated with factor analysis of aerosol mass spectrometer (AMS) data into hydrocarbon-like OA (HOA) and oxygenated OA (OOA). We develop a new method to parameterize H:C of OOA in terms of f43 (ratio of m/z 43, mostly C2H3O+, to total signal in the component mass spectrum). Such parameterization allows the transformation of large database of ambient OOA components from the f44 (mostly CO2+, likely from acid groups) vs. f43 space ("triangle plot") (Ng et al., 2010) into the Van Krevelen diagram (H:C vs. O:C). Heald et al. (2010) suggested that the bulk composition of OA line up in the Van Krevelen diagram with a slope ~ -1; such slope can potentially arise from the physical mixing of HOA and OOA, and/or from chemical aging of these components. In this study, we find that the OOA components from all sites occupy an area in the Van Krevelen space, with the evolution of OOA following a shallower slope of ~ -0.5, consistent with the additions of both acid and alcohol functional groups without fragmentation, and/or the addition of acid groups with C-C bond breakage. The importance of acid formation in OOA evolution is consistent with increasing f44 in the triangle plot with photochemical age. These results provide a framework for linking the bulk aerosol chemical composition evolution to molecular-level studies.

  6. Factor analysis of combined organic and inorganic aerosol mass spectra from high resolution aerosol mass spectrometer measurements

    NASA Astrophysics Data System (ADS)

    Sun, Y. L.; Zhang, Q.; Schwab, J. J.; Yang, T.; Ng, N. L.; Demerjian, K. L.

    2012-05-01

    The high resolution mass spectra of organic and inorganic aerosols from aerosol mass spectrometer (AMS) measurements were first combined into positive matrix factorization (PMF) analysis to investigate the sources and evolution processes of atmospheric aerosols. The new approach is able to study the mixing of organic aerosols (OA) and inorganic species, the acidity of OA factors, and the fragment ion patterns related to photochemical processing. In this study, PMF analysis of the unified AMS spectral matrices resolved 8 factors for the submicron aerosols measured at Queens College in New York City in summer 2009. The hydrocarbon-like OA (HOA) and cooking OA (COA) contain very minor inorganic species, indicating the different sources and mixing characteristics between primary OA and secondary species. The two factors that are primarily ammonium sulfate (SO4-OA) and ammonium nitrate (NO3-OA), respectively, are overall neutralized, of which the OA in SO4-OA shows the highest oxidation state (O/C = 0.69) among OA factors. The semi-volatile oxygenated OA comprises two components, i.e., a less oxidized (LO-OOA) and a more oxidized (MO-OOA). The MO-OOA represents a local photochemical product with the diurnal profile exhibiting a pronounced noon peak, consistent with those of formaldehyde (HCHO) and Ox (= O3+NO2). The much higher NO+/NO2+ fragment ion ratio in MO-OOA than that from ammonium nitrate alone provides evidence for the formation of organic nitrates. The amine-related nitrogen-enriched OA (NOA) contains ~25% of acidic inorganic salts, elucidating the formation of secondary OA from amines in acidic environments. The size distributions derived from 3-dimensional size-resolved mass spectra show distinct diurnal evolving behaviors for different OA factors, but overall a progressing evolution from smaller to larger particle mode as a function of oxidation states. Our results demonstrate that PMF analysis by incorporating inorganic aerosols is of importance for

  7. Mass Spectrometry of Atmospheric Aerosol: 1 nanometer to 1 micron

    NASA Astrophysics Data System (ADS)

    Worsnop, D. R.; Ehn, M.; Junninen, H.; Kulmala, M. T.

    2010-12-01

    The role of aerosol particles remains the largest uncertainty in quantitatively assessing past, current and future climate change. The principal reason for that uncertainty arises from the need to characterize and model composition and size dependent aerosol processes, ranging from nanometer to micron scales. Aerosol mass spectrometry results have shown that about half the sub-micron aerosol composition is composed of highly oxygenated organics that are not well understood in terms of photochemical reaction mechanisms (Jimenez et al, 2009). This work has included application of high resolution time-of-flight mass spectrometry (ToFMS) in order to determine elemental and functional group composition of complex organic components. Recently, we have applied similar ToFMS to determine the composition of ambient ions, molecules and clusters, potentially involved in formation and growth of nano-particles (Junninen et al, 2010). Observed organic anions (molecular weight range 200-500 Th) have similar chemical composition as the least volatile secondary organics observed in fine particles; while organic cations are dominated by amines and pyridines. During nucleation events, anions are dominated by sulphuric acid cluster ions (Ehn et al, 2010). In both nanometer and micrometer size ranges, the goal to elucidate the roles of inorganic and organic species, particularly how particle evolution and physical properties depend on mixed compositions. Recent results will be discussed, including ambient and experimental chamber observations. Ehn et al, Atmos. Chem. Phys. Discuss., 10, 14897-14946, 2010 Jimenez et al, Science, 326, 1525-1529, 2009 Junninen et al, Atmos. Meas. Tech., 3, 1039-1053, 2010

  8. In situ vertical profiles of aerosol extinction, mass, and composition over the southeast United States during SENEX and SEAC4RS: observations of a modest aerosol enhancement aloft

    NASA Astrophysics Data System (ADS)

    Wagner, N. L.; Brock, C. A.; Angevine, W. M.; Beyersdorf, A.; Campuzano-Jost, P.; Day, D. A.; de Gouw, J. A.; Diskin, G. S.; Gordon, T. D.; Graus, M. G.; Huey, G.; Jimenez, J. L.; Lack, D. A.; Liao, J.; Liu, X.; Markovic, M. Z.; Middlebrook, A. M.; Mikoviny, T.; Peischl, J.; Perring, A. E.; Richardson, M. S.; Ryerson, T. B.; Schwarz, J. P.; Warneke, C.; Welti, A.; Wisthaler, A.; Ziemba, L. D.; Murphy, D. M.

    2015-02-01

    Vertical profiles of submicron aerosol over the southeastern United States (SEUS) during the summertime from in situ aircraft-based measurements were used to construct aggregate profiles of chemical, microphysical, and optical properties. Shallow cumulus convection was observed during many profiles. These conditions enhance vertical transport of trace gases and aerosol and create a cloudy transition layer on top of the sub-cloud mixed layer. The trace gas and aerosol concentrations in the transition layer were modeled as a mixture with contributions from the mixed layer below and the free troposphere above. The amount of vertical mixing, or entrainment of air from the free troposphere, was quantified using the observed mixing ratio of carbon monoxide (CO). Although the median aerosol mass, extinction, and volume decreased with altitude in the transition layer, they were ~10% larger than expected from vertical mixing alone. This enhancement was likely due to secondary aerosol formation in the transition layer. Although the transition layer enhancements of the particulate sulfate and organic aerosol (OA) were both similar in magnitude, only the enhancement of sulfate was statistically significant. The column integrated extinction, or aerosol optical depth (AOD), was calculated for each individual profile, and the transition layer enhancement of extinction typically contributed less than 10% to the total AOD. Our measurements and analysis were motivated by two recent studies that have hypothesized an enhanced layer of secondary organic aerosol (SOA) aloft to explain the summertime enhancement of AOD (2-3 times greater than winter) over the southeastern United States. In contrast to this hypothesis, the modest enhancement we observed in the transition layer was not dominated by OA and was not a large fraction of the summertime AOD.

  9. Stratospheric sulfuric acid fraction and mass estimate for the 1982 volcanic eruption of El Chichon

    NASA Technical Reports Server (NTRS)

    Hofmann, D. J.; Rosen, J. M.

    1983-01-01

    The stratospheric sulfuric acid fraction and mass for the 1982 volcanic eruptions of El Chichon are investigated using data from balloon soundings at Laramie (41 deg N) and in southern Texas (27-29 deg N). The total stratospheric mass of these eruptions is estimated to be approximately 8 Tg about 6.5 months after the eruption with possibly as much as 20 Tg in the stratosphere about 45 days after the eruption. Observations of the aerosol in Texas revealed two primary layers, both highly volatile at 150 C. Aerosol in the upper layer at about 25 km was composed of an approximately 80 percent H2SO4 solution while the lower layer at approximately 18 km was composed of a 60-65 percent H2SO4 solution aerosol. It is calculated that an H2SO4 vapor concentration of at least 3 x 10 to the 7th molecules/cu cm is needed to sustain the large droplets in the upper layer. An early bi-modal nature in the size distribution indicates droplet nucleation from the gas phase during the first 3 months, while the similarity of the large particle profiles 2 months apart shows continued particle growth 6.5 months after the explosion.

  10. Changes in organic aerosol composition with aging inferred from aerosol mass spectra

    NASA Astrophysics Data System (ADS)

    Ng, N. L.; Canagaratna, M. R.; Jimenez, J. L.; Chhabra, P. S.; Seinfeld, J. H.; Worsnop, D. R.

    2011-07-01

    Organic aerosols (OA) can be separated with factor analysis of aerosol mass spectrometer (AMS) data into hydrocarbon-like OA (HOA) and oxygenated OA (OOA). We develop a new method to parameterize H:C of OOA in terms of f43 (ratio of m/z 43, mostly C2H3O+, to total signal in the component mass spectrum). Such parameterization allows for the transformation of large database of ambient OOA components from the f44 (mostly CO2+, likely from acid groups) vs. f43 space ("triangle plot") (Ng et al., 2010) into the Van Krevelen diagram (H:C vs. O:C) (Van Krevelen, 1950). Heald et al. (2010) examined the evolution of total OA in the Van Krevelen diagram. In this work total OA is deconvolved into components that correspond to primary (HOA and others) and secondary (OOA) organic aerosols. By deconvolving total OA into different components, we remove physical mixing effects between secondary and primary aerosols which allows for examination of the evolution of OOA components alone in the Van Krevelen space. This provides a unique means of following ambient secondary OA evolution that is analogous to and can be compared with trends observed in chamber studies of secondary organic aerosol formation. The triangle plot in Ng et al. (2010) indicates that f44 of OOA components increases with photochemical age, suggesting the importance of acid formation in OOA evolution. Once they are transformed with the new parameterization, the triangle plot of the OOA components from all sites occupy an area in Van Krevelen space which follows a ΔH:C/ΔO:C slope of ~ -0.5. This slope suggests that ambient OOA aging results in net changes in chemical composition that are equivalent to the addition of both acid and alcohol/peroxide functional groups without fragmentation (i.e. C-C bond breakage), and/or the addition of acid groups with fragmentation. These results provide a framework for linking the bulk aerosol chemical composition evolution to molecular-level studies.

  11. Urban air quality assessment using monitoring data of fractionized aerosol samples, chemometrics and meteorological conditions.

    PubMed

    Yotova, Galina I; Tsitouridou, Roxani; Tsakovski, Stefan L; Simeonov, Vasil D

    2016-01-01

    The present article deals with assessment of urban air by using monitoring data for 10 different aerosol fractions (0.015-16 μm) collected at a typical urban site in City of Thessaloniki, Greece. The data set was subject to multivariate statistical analysis (cluster analysis and principal components analysis) and, additionally, to HYSPLIT back trajectory modeling in order to assess in a better way the impact of the weather conditions on the pollution sources identified. A specific element of the study is the effort to clarify the role of outliers in the data set. The reason for the appearance of outliers is strongly related to the atmospheric condition on the particular sampling days leading to enhanced concentration of pollutants (secondary emissions, sea sprays, road and soil dust, combustion processes) especially for ultra fine and coarse particles. It is also shown that three major sources affect the urban air quality of the location studied-sea sprays, mineral dust and anthropogenic influences (agricultural activity, combustion processes, and industrial sources). The level of impact is related to certain extent to the aerosol fraction size. The assessment of the meteorological conditions leads to defining of four downwind patterns affecting the air quality (Pelagic, Western and Central Europe, Eastern and Northeastern Europe and Africa and Southern Europe). Thus, the present study offers a complete urban air assessment taking into account the weather conditions, pollution sources and aerosol fractioning. PMID:26942452

  12. Viscoelastic bearings with fractional constitutive law for fractional tuned mass dampers

    NASA Astrophysics Data System (ADS)

    Barone, G.; Di Paola, M.; Lo Iacono, F.; Navarra, G.

    2015-05-01

    The paper aims at studying the effects of the inherent fractional constitutive law of viscoelastic bearings used as devices for tuned mass dampers. First, the proper constitutive law of the viscoelastic supports is determined by the local constitutive law. Then, the characteristic force-displacement relationship at the top of the bearing is found. Taking advantage of the whole bearing constitutive laws, the tuning of the mass damper is proposed by defining the damped fractional frequency, which is analogous to the classical damped frequency. The effectiveness of the optimal tuning procedure is validated by a numerical application on a system subjected to a Gaussian white noise.

  13. Characterization of primary organic aerosol emissions from meat cooking, trash burning, and motor vehicles with high-resolution aerosol mass spectrometry and comparison with ambient and chamber observations.

    PubMed

    Mohr, Claudia; Huffman, Alex; Cubison, Michael J; Aiken, Allison C; Docherty, Kenneth S; Kimmel, Joel R; Ulbrich, Ingrid M; Hannigan, Michael; Jimenez, Jose L

    2009-04-01

    Organic aerosol (OA) emissions from motor vehicles, meat-cooking and trash burning are analyzed here using a high-resolution aerosol mass spectrometer (AMS). High resolution data show that aerosols emitted by combustion engines and plastic burning are dominated by hydrocarbon-like organic compounds. Meat cooking and especially paper burning emissions contain significant fractions of oxygenated organic compounds; however, their unit-resolution mass spectral signatures are very similar to those from ambient hydrocarbon-like OA, and very different from the mass spectra of ambient secondary or oxygenated OA (OOA). Thus, primary OA from these sources is unlikelyto be a significant direct source of ambient OOA. There are significant differences in high-resolution tracer m/zs that may be useful for differentiating some of these sources. Unlike in most ambient spectra, all of these sources have low total m/z 44 and this signal is not dominated by the CO2+ ion. All sources have high m/z 57, which is low during high OOA ambient periods. Spectra from paper burning are similar to some types of biomass burning OA, with elevated m/z 60. Meat cooking aerosols also have slightly elevated m/z 60, whereas motor vehicle emissions have very low signal at this m/z. PMID:19452899

  14. Investigating types and sources of organic aerosol in Rocky Mountain National Park using aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Schurman, M. I.; Lee, T.; Sun, Y.; Schichtel, B. A.; Kreidenweis, S. M.; Collett, J. L., Jr.

    2015-01-01

    The environmental impacts of atmospheric particles are highlighted in remote areas where visibility and ecosystem health can be degraded by even relatively low particle concentrations. Submicron particle size, composition, and source apportionment were explored at Rocky Mountain National Park using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer. This summer campaign found low average, but variable, particulate mass (PM) concentrations (max = 93.1 μg m-3, avg. = 5.13 ± 2.72 μg m-3) of which 75.2 ± 11.1% is organic. Low-volatility oxidized organic aerosol (LV-OOA, 39.3% of PM1 on average) identified using Positive Matrix Factorization appears to be mixed with ammonium sulfate (3.9% and 16.6% of mass, respectively), while semi-volatile OOA (27.6%) is correlated with ammonium nitrate (nitrate: 4.3%); concentrations of these mixtures are enhanced with upslope (SE) surface winds from the densely populated Front Range area, indicating the importance of transport. A local biomass burning organic aerosol (BBOA, 8.4%) source is suggested by mass spectral cellulose combustion markers (m/z 60 and 73) limited to brief, high-concentration, polydisperse events (suggesting fresh combustion), a diurnal maximum at 22:00 local standard time when campfires were set at adjacent summer camps, and association with surface winds consistent with local campfire locations. The particle characteristics determined here represent typical summertime conditions at the Rocky Mountain site based on comparison to ~10 years of meteorological, particle composition, and fire data.

  15. Investigating types and sources of organic aerosol in Rocky Mountain National Park using aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Schurman, M. I.; Lee, T.; Sun, Y.; Schichtel, B. A.; Kreidenweis, S. M.; Collett, J. L., Jr.

    2014-07-01

    The environmental impacts of atmospheric particles are highlighted in remote areas where visibility and ecosystem health can be degraded by even relatively low particle concentrations. Submicron particle size, composition, and source apportionment were explored at Rocky Mountain National Park using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer. This summer campaign found low average, but variable, particulate mass (PM) concentrations (max = 93.1 μg m-3, avg. = 5.13 ± 2.72 μg m-3) of which 75.2 ± 11.1% is organic. Low-volatility oxidized organic aerosol (LV-OOA, 39.3% of PM1 on average) identified using Positive Matrix Factorization appears to be mixed with ammonium sulfate (3.9 and 16.6% of mass, respectively), while semi-volatile OOA (27.6%) is correlated with ammonium nitrate (nitrate: 4.3%); concentrations of these mixtures are enhanced with upslope (SE) surface winds from the densely populated Front Range area, indicating the importance of transport. A local biomass burning organic aerosol (BBOA, 8.4%) source is suggested by mass spectral cellulose combustion markers (m/zs 60 and 73) limited to brief, high-concentration, polydisperse events (suggesting fresh combustion), a diurnal maximum at 22:00 local standard time (LST) when campfires were set at adjacent summer camps, and association with surface winds consistent with local campfire locations. The particle characteristics determined here represent typical summertime conditions at the Rocky Mountain site based on comparison to ∼10 years of meteorological, particle composition, and fire data.

  16. 40 CFR Table F-5 to Subpart F of... - Estimated Mass Concentration Measurement of PM2.5 for Idealized “Typical” Coarse Aerosol Size...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 5 2011-07-01 2011-07-01 false Estimated Mass Concentration... 53—Estimated Mass Concentration Measurement of PM2.5 for Idealized “Typical” Coarse Aerosol Size Distribution Particle Aerodynamic Diameter (µm) Test Sampler Fractional Sampling Effectiveness Interval...

  17. 40 CFR Table F-5 to Subpart F of... - Estimated Mass Concentration Measurement of PM 2.5 for Idealized “Typical” Coarse Aerosol Size...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 6 2014-07-01 2014-07-01 false Estimated Mass Concentration... 53—Estimated Mass Concentration Measurement of PM 2.5 for Idealized “Typical” Coarse Aerosol Size Distribution Particle Aerodynamic Diameter (µm) Test Sampler Fractional Sampling Effectiveness Interval...

  18. 40 CFR Table F-5 to Subpart F of... - Estimated Mass Concentration Measurement of PM2.5 for Idealized “Typical” Coarse Aerosol Size...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 6 2012-07-01 2012-07-01 false Estimated Mass Concentration... 53—Estimated Mass Concentration Measurement of PM2.5 for Idealized “Typical” Coarse Aerosol Size Distribution Particle Aerodynamic Diameter (µm) Test Sampler Fractional Sampling Effectiveness Interval...

  19. 40 CFR Table F-5 to Subpart F of... - Estimated Mass Concentration Measurement of PM 2.5 for Idealized “Typical” Coarse Aerosol Size...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 6 2013-07-01 2013-07-01 false Estimated Mass Concentration... 53—Estimated Mass Concentration Measurement of PM 2.5 for Idealized “Typical” Coarse Aerosol Size Distribution Particle Aerodynamic Diameter (µm) Test Sampler Fractional Sampling Effectiveness Interval...

  20. 40 CFR Table F-5 to Subpart F of... - Estimated Mass Concentration Measurement of PM2.5 for Idealized “Typical” Coarse Aerosol Size...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Estimated Mass Concentration... 53—Estimated Mass Concentration Measurement of PM2.5 for Idealized “Typical” Coarse Aerosol Size Distribution Particle Aerodynamic Diameter (µm) Test Sampler Fractional Sampling Effectiveness Interval...

  1. Study of the Tropospheric Aerosol Structure Under Changing of the Air Mass Type from Lidar Observations in Tomsk

    NASA Astrophysics Data System (ADS)

    Samoilova, S. V.; Balin, Yu. S.; Kokhanenko, G. P.; Penner, I. É.

    2016-04-01

    The aerosol optical characteristics in the main tropospheric layers are investigated based on joint interpretation of data of multi-frequency lidar sensing (110 sessions) and results of modeling of back air mass trajectories. Methodical problems for separating layers with different scattering properties and estimating their vertical boundaries are considered. Three optical criteria are simultaneously used to distinguish aerosol layers from cloud formations, including the gradient of the backscattering coefficient, optical depth, and the depolarization ratio. High values of the lidar ratio (66 sr) and of the Angstrom exponent (1.62) in the shortwavelength spectral range are observed in the boundary layer for Arctic transport. At the same time, low values of these optical parameters are characteristic for Asian transport: the lidar ratio is 54 sr and the Angstrom exponent is 1.1, which is explained by different relative contributions of the coarse and fine aerosol fractions to the air mass.

  2. The effects of loaded carrier mass and formulation mass on aerosolization efficiency in dry powder inhaler devices.

    PubMed

    Ooi, Jesslynn; Gill, Charlotte; Young, Paul M; Traini, Daniela

    2015-01-01

    Previous studies have suggested that particle-particle impaction may influence aerosolization properties in carrier-based dry powder inhalers, through transfer of kinetic energy from large carriers to surface-deposited active drug. The importance of particle-particle collision has yet to be compared against other mechanisms that could lead to drug liberation, such as particle-wall impaction and turbulence. In particular, particle-particle collisions are difficult to model in silico due to computational restrictions. This study investigated the effects of dry powder inhaler particle-particle collisions in vitro using an established carrier-drug model dry powder inhalation formulation. Spherical polystyrene beads of median size 82.80 μm were chosen as a model carrier as they were of uniform size, shape, surface area, density, porosity and hardness and thus eliminated potential variables that would have conflicted with the study. This model carrier was geometrically blended with micronized salbutamol sulphate (loaded blend). The correlation between the mass of loaded blend (5-40 mg) in the Rotahaler® DPI device and resulting fine particle fraction (FPF) was examined at a constant flow rate of 60 L.min(-1). In a second experiment, the mass of loaded blend was kept constant and a variable amount of blank carrier particles were added to the Rotahaler® device to ascertain if additional "blank" carrier particles affected the final FPF. The efficiency of aerosolization remained constant with varying amounts of blank carrier particles as determined by the fine particle fraction of the emitted dose (FPFED) and fine particle fraction of the loaded dose (FPFLD). No statistical difference in FPFED and FPFLD values were observed for increasing masses of blank carrier. In addition, no statistical difference in FPFED and FPFLD between the two experiments was obtained. These observations suggest that particle-particle collisions are not a driving mechanism responsible for

  3. Aerosol characterization over the southeastern United States using high resolution aerosol mass spectrometry: spatial and seasonal variation of aerosol composition, sources, and organic nitrates

    NASA Astrophysics Data System (ADS)

    Xu, L.; Suresh, S.; Guo, H.; Weber, R. J.; Ng, N. L.

    2015-04-01

    We deployed a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and an Aerosol Chemical Speciation Monitor (ACSM) to characterize the chemical composition of submicron non-refractory particles (NR-PM1) in the southeastern US. Measurements were performed in both rural and urban sites in the greater Atlanta area, GA and Centreville, AL for approximately one year, as part of Southeastern Center of Air Pollution and Epidemiology study (SCAPE) and Southern Oxidant and Aerosol Study (SOAS). Organic aerosol (OA) accounts for more than half of NR1 mass concentration regardless of sampling sites and seasons. Positive matrix factorization (PMF) analysis of HR-ToF-AMS measurements identified various OA sources, depending on location and season. Hydrocarbon-like OA (HOA) and cooking OA (COA) have important but not dominant contributions to total OA in urban sites. Biomass burning OA (BBOA) concentration shows a distinct seasonal variation with a larger enhancement in winter than summer. We find a good correlation between BBOA and brown carbon, indicating biomass burning is an important source for brown carbon, although an additional, unidentified brown carbon source is likely present at the rural Yorkville site. Isoprene-derived OA (Isoprene-OA) is only deconvolved in warmer months and contributes 18-36% of total OA. The presence of Isoprene-OA factor in urban sites is more likely from local production in the presence of NOx than transport from rural sites. More-oxidized and less-oxidized oxygenated organic aerosol (MO-OOA and LO-OOA, respectively) are dominant fractions (47-79%) of OA in all sites. MO-OOA correlates well with ozone in summer, but not in winter, indicating MO-OOA sources may vary with seasons. LO-OOA, which reaches a daily maximum at night, correlates better with estimated nitrate functionality from organic nitrates than total nitrates. Based on the HR-ToF-AMS measurements, we estimate that the nitrate functionality from organic nitrates

  4. Ambient Observations of Organic Nitrogen Compounds in Submicrometer Aerosols in New York Using High Resolution Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Zhou, S.; Ge, X.; Xu, J.; Sun, Y.; Zhang, Q.

    2015-12-01

    Organic nitrogen (ON) compounds, which include amines, nitriles, organic nitrates, amides, and N-containing aromatic heterocycles, are an important class of compounds ubiquitously detected in atmospheric particles and fog and cloud droplets. Previous studies indicate that these compounds can make up a significant fraction (20-80%) of the total nitrogen (N) content in atmospheric condensed phases and play important roles in new particle formation and growth and affecting the optical and hygroscopicity of aerosols. In this study, we report the observation of ON compounds in submicrometer particles (PM1) at two locations in New York based on measurements using Aerodyne high-resolution time-of-flight mass spectrometer (HR-ToF-AMS). One study was conducted as part of the US Department of Energy funded Aerosol Lifecyle - Intensive Operation Period (ALC-IOP) campaign at Brookhaven National Lab (BNL, 40.871˚N, 72.89˚W) in summer, 2011 and the other was conducted at the Queen's College (QC) in New York City (NYC) in summer, 2009. We observed a notable amount of N-containing organic fragment ions, CxHyNp+ and CxHyOzNp+, in the AMS spectra of organic aerosols at both locations and found that they were mainly associated with amino functional groups. Compared with results from lab experiments, the C3H8N+ at m/z = 58 was primarily attributed to trimethylamine. In addition, a significant amount of organonitrates was observed at BNL. Positive matrix factorization (PMF) analysis of the high resolution mass spectra (HRMS) of organic aerosols identified a unique nitrogen-enriched OA (NOA) factor with elevated nitrogen-to-carbon (N/C) at both BNL and QC. Analysis of the size distributions, volatility profiles, and correlations with external tracer indicates that acid-base reactions of amino compounds with sulfate and acidic gas were mainly responsible for the formation of amine salts. Photochemical production was also observed to play a role in the formation of NOA. Bivariate polar

  5. The link between organic aerosol mass loading and degree of oxygenation: an α-pinene photooxidation study

    NASA Astrophysics Data System (ADS)

    Pfaffenberger, L.; Barmet, P.; Slowik, J. G.; Praplan, A. P.; Dommen, J.; Prévôt, A. S. H.; Baltensperger, U.

    2012-09-01

    A series of smog chamber (SC) experiments was conducted to identify driving factors responsible for the discrepancy between ambient and SC aerosol degree of oxygenation. An Aerodyne high resolution time-of-flight aerosol mass spectrometer is used to compare mass spectra from α-pinene photooxidation with ambient aerosol. Composition is compared in terms of the fraction of organic mass measured at m/z 44 (f44), a surrogate for carboxylic/organic acids as well as the atomic oxygen-to-carbon ratio (O : C), vs. f43, a surrogate for aldehydes, alcohols and ketones. Low (near-ambient) organic mass concentrations were found to be necessary to obtain oxygenation levels similar to those of low-volatility oxygenated organic aerosol (LV-OOA) commonly identified in ambient measurements. The effects of organic mass loading and OH (hydroxyl radical) exposure were decoupled by inter-experiment comparisons at the same integrated OH concentration. On average, an OH exposure of 2.9 ± 1.3 × 107 cm-3 h is needed to increase f44 by 1% during aerosol aging. For the first time, LV-OOA-like aerosol from the abundant biogenic precursor α-pinene was produced in a smog chamber by oxidation at typical atmospheric OH concentrations. Significant correlation between measured secondary organic aerosol (SOA) and reference LV-OOA mass spectra is shown by Pearson's R2 values larger than 0.90 for experiments with low organic mass concentrations between 1.5 and 15 μg m-3 at an OH exposure of 4 × 107 cm-3 h, corresponding to about two days oxidation time in the atmosphere, based on a global mean OH concentration of ∼1 × 106 cm-3. Not only is the α-pinene SOA more oxygenated at low organic mass loadings, but the functional dependence of oxygenation on mass loading is enhanced at atmospherically-relevant precursor concentrations. Since the degree of oxygenation influences the chemical, volatility and hygroscopic properties of ambient aerosol, smog chamber studies must be performed at near

  6. Aerosols in polluted versus nonpolluted air masses Long-range transport and effects on clouds

    NASA Technical Reports Server (NTRS)

    Pueschel, R. F.; Van Valin, C. C.; Castillo, R. C.; Kadlecek, J. A.; Ganor, E.

    1986-01-01

    To assess the influence of anthropogenic aerosols on the physics and chemistry of clouds in the northeastern United States, aerosol and cloud-drop size distributions, elemental composition of aerosols as a function of size, and ionic content of cloud water were measured on Whiteface Mountain, NY, during the summers of 1981 and 1982. In several case studies, the data were cross-correlated with different air mass types - background continental, polluted continental, and maritime - that were advected to the sampling site. The results are the following: (1) Anthropogenic sources hundreds of kilometers upwind cause the small-particle (accumulation) mode number to increase from hundreds of thousands per cubic centimeter and the mass loading to increase from a few to several tens of micrograms per cubic meter, mostly in the form of sulfur aerosols. (2) A significant fraction of anthropogenic sulfur appears to act as cloud condensation nuclei (CCN) to affect the cloud drop concentration. (3) Clouds in Atlantic maritime air masses have cloud drop spectra that are markedly different from those measured in continental clouds. The drop concentration is significantly lower, and the drop size spectra are heavily skewed toward large drops. (4) Effects of anthropogenic pollutants on cloud water ionic composition are an increase of nitrate by a factor of 50, an increase of sulfate by more than one order of magnitude, and an increase of ammonium ion by a factor of 7. The net effect of the changes in ionic concentrations is an increase in cloud water acidity. An anion deficit even in maritime clouds suggests an unknown, possibly biogenic, source that could be responsible for a pH below neutral, which is frequently observed in nonpolluted clouds.

  7. An explicit study of aerosol mass conversion and its parameterization in warm rain formation of cumulus clouds

    NASA Astrophysics Data System (ADS)

    Sun, J.; Fen, J.; Ungar, R. K.

    2013-10-01

    The life time of atmospheric aerosols is highly affected by in-cloud scavenging processes. Aerosol mass conversion from aerosols embedded in cloud droplets into aerosols embedded in raindrops is a pivotal pathway for wet removal of aerosols in clouds. The aerosol mass conversion rate in the bulk microphysics parameterizations is always assumed to be linearly related to the precipitation production rate, which includes the cloud water autoconversion rate and the cloud water accretion rate. The ratio of the aerosol mass concentration conversion rate to the cloud aerosol mass concentration has typically been considered to be the same as the ratio of the precipitation production rate to the cloud droplet mass concentration. However, the mass of an aerosol embedded in a cloud droplet is not linearly proportional to the mass of the cloud droplet. A simple linear relationship cannot be drawn between the precipitation production rate and the aerosol mass concentration conversion rate. In this paper, we studied the evolution of aerosol mass concentration conversion rates in a warm rain formation process with a 1.5-dimensional non-hydrostatic convective cloud and aerosol interaction model in the bin microphysics. We found that the ratio of the aerosol mass conversion rate to the cloud aerosol mass concentration can be statistically expressed by the ratio of the precipitation production rate to the cloud droplet mass concentration with an exponential function. We further gave some regression equations to determine aerosol conversions in the warm rain formation under different threshold radii of raindrops and different aerosol size distributions.

  8. Mass fractionation of the lunar surface by solar wind sputtering

    NASA Technical Reports Server (NTRS)

    Switkowski, Z. E.; Haff, P. K.; Tombrello, T. A.; Burnett, D. S.

    1975-01-01

    The sputtering of the lunar surface by the solar wind is examined as a possible mechanism of mass fractionation. Simple arguments based on current theories of sputtering and the ballistics of the sputtered atoms suggest that most ejected atoms will have sufficiently high energy to escape lunar gravity. However, the fraction of atoms which falls back to the surface is enriched in the heavier atomic components relative to the lighter ones. This material is incorporated into the heavily radiation-damaged outer surfaces of grains where it is subject to resputtering. Over the course of several hundred years an equilibrium surface layer, enriched in heavier atoms, is found to form. The dependence of the calculated results upon the sputtering rate and on the details of the energy spectrum of sputtered particles is investigated. It is concluded that mass fractionation by solar wind sputtering is likely to be an important phenomenon on the lunar surface.

  9. Seasonal differences in aerosol water may reconcile AOT and surface mass measurements in the Southeast U.S.

    NASA Astrophysics Data System (ADS)

    Nguyen, T. K. V.; Ghate, V. P.; Carlton, A. M. G.

    2015-12-01

    Summertime aerosol optical thickness (AOT) in the Southeast U.S. is high and sharply enhanced (2-3 times) compared to wintertime AOT. This seasonal pattern is unique to the Southeast U.S. and is of particular interest because temperatures there have not warmed over the past 100 years, contrasting with trends in other U.S. regions. Some investigators hypothesize the Southeast temperature trend is due to secondary organic aerosols (SOA) formed from interactions of biogenic volatile organic compounds (BVOCs) and anthropogenic emissions that create a cooling haze. However, aerosol measurements made at the surface do not exhibit strong seasonal differences in mass or organic fraction to support this hypothesis. In this work, we attempt to reconcile the spatial and temporal distribution of AOT over the U.S. with surface mass measurements by examining trends in particle-phase liquid water, an aerosol constituent that effectively scatters radiation and is removed from aerosols in mass measurements at routine surface monitoring sites. We employ the thermodynamic model ISORROPIA (v2.1) to estimate surface and aloft aerosol water mass concentrations at locations of Interagency Monitoring of Protected Visual Environments (IMPROVE) sites using measured speciated ion mass concentrations and NCEP North American Regional Reanalysis (NARR) meteorological data. Results demonstrate strong seasonal differences in aerosol water in the eastern compared to the western part of the U.S., consistent with geographic patterns in AOT. The highest mean regional seasonal difference from 2000 to 2007 is 5.5 μg m-3 and occurs the Southeast, while the lowest is 0.44 μg m-3 and occurs in the dry Mountain West. Our findings suggest 1) similarity between spatial trends in aerosol water in the U.S. and previously published AOT data from the MODIS-TERRA instrument and 2) similar interannual trends in mean aerosol water and previously published interannual AOT trends from MISR, MODIS-TERRA, MODIS

  10. A CLOSURE STUDY OF AEROSOL MASS CONCENTRATION MEASUREMENTS: COMPARISON OF VALUES OBTAINED WITH FILTERS AND BY DIRECT MEASUREMENTS OF MASS DISTRIBUTIONS. (R826372)

    EPA Science Inventory

    We compare measurements of aerosol mass concentrations obtained gravimetrically using Teflon coated glass fiber filters and by integrating mass distributions measured with the differential mobility analyzer–aerosol particle mass analyzer (DMA–APM) technique (Aero...

  11. Hemispheric asymmetry in aerosol optical thickness and cloud fraction over the tropical Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Kishcha, Pavel; Starobinets, Boris; da Silva, Arlindo; Long, Charles; Kalashnikova, Olga; Alpert, Pinhas

    2015-04-01

    Hemispheric asymmetry in cloud fraction and aerosols could lead to hemispheric imbalance in solar radiation reaching the surface and, consequently, could affect the Earth radiation budget. Previous studies showed that, over the global ocean, there is no noticeable hemispheric asymmetry in cloud fraction (CF). This contributes to the balance in solar radiation reaching the sea surface in the Northern and Southern hemispheres. In the current study, we focus on the tropical Atlantic (30oN - 30oS) which is characterized by significant amounts of Saharan dust dominating other aerosol species over the North Atlantic. Our main point is that, over the tropical Atlantic, not only is Saharan dust responsible for the pronounced hemispheric aerosol asymmetry, but it also contributes to significant cloud cover along the Saharan Air Layer. This could lead to the hemispheric imbalance in strong solar radiation reaching the sea surface in the tropical Atlantic. During the 10-year study period (July 2002 - June 2012), NASA Aerosol Reanalysis (aka MERRAero) showed that, when the hemispheric asymmetry in dust aerosol optical thickness (AOT) was the most pronounced (particularly in July), dust AOT averaged separately over the tropical North Atlantic was one order of magnitude higher than that averaged over the tropical South Atlantic. In the presence of such strong hemispheric asymmetry in dust AOT in July, CF averaged separately over the tropical North Atlantic exceeded that over the tropical South Atlantic by 20%. In July, along the Saharan Air Layer, Moderate Resolution Imaging Spectroradiometer (MODIS) CF data showed significant cloud cover (up to 0.8 - 0.9). This significant cloud fraction along SAL together with clouds over the Atlantic Inter-tropical Convergence Zone contributes to the above-mentioned hemispheric CF asymmetry. Both Multi-Angle Imaging SpectroRadiometer (MISR) measurements and MERRAero data were in agreement on seasonal variations in hemispheric aerosol

  12. A new method to discriminate secondary organic aerosols from different sources using high-resolution aerosol mass spectra

    NASA Astrophysics Data System (ADS)

    Heringa, M. F.; Decarlo, P. F.; Chirico, R.; Tritscher, T.; Clairotte, M.; Mohr, C.; Crippa, M.; Slowik, J. G.; Pfaffenberger, L.; Dommen, J.; Weingartner, E.; Prévôt, A. S. H.; Baltensperger, U.

    2012-02-01

    Organic aerosol (OA) represents a significant and often major fraction of the non-refractory PM1 (particulate matter with an aerodynamic diameter da < 1 μm) mass. Secondary organic aerosol (SOA) is an important contributor to the OA and can be formed from biogenic and anthropogenic precursors. Here we present results from the characterization of SOA produced from the emissions of three different anthropogenic sources. SOA from a log wood burner, a Euro 2 diesel car and a two-stroke Euro 2 scooter were characterized with an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS) and compared to SOA from α-pinene. The emissions were sampled from the chimney/tailpipe by a heated inlet system and filtered before injection into a smog chamber. The gas phase emissions were irradiated by xenon arc lamps to initiate photo-chemistry which led to nucleation and subsequent particle growth by SOA production. Duplicate experiments were performed for each SOA type, with the averaged organic mass spectra showing Pearson's r values >0.94 for the correlations between the four different SOA types after five hours of aging. High-resolution mass spectra (HR-MS) showed that the dominant peaks in the MS, m/z 43 and 44, are dominated by the oxygenated ions C2H3O+ and CO2+, respectively, similarly to the relatively fresh semi-volatile oxygenated OA (SV-OOA) observed in the ambient aerosol. The atomic O:C ratios were found to be in the range of 0.25-0.55 with no major increase during the first five hours of aging. On average, the diesel SOA showed the lowest O:C ratio followed by SOA from wood burning, α-pinene and the scooter emissions. Grouping the fragment ions revealed that the SOA source with the highest O:C ratio had the largest fraction of small ions. The HR data of the four sources could be clustered and separated using principal component analysis (PCA). The model showed a significant separation of the four SOA types and clustering of the duplicate

  13. A new method to discriminate secondary organic aerosols from different sources using high-resolution aerosol mass spectra

    NASA Astrophysics Data System (ADS)

    Heringa, M. F.; Decarlo, P. F.; Chirico, R.; Tritscher, T.; Clairotte, M.; Mohr, C.; Crippa, M.; Slowik, J. G.; Pfaffenberger, L.; Dommen, J.; Weingartner, E.; Prévôt, A. S. H.; Baltensperger, U.

    2011-10-01

    Organic aerosol (OA) represents a significant and often major fraction of the non-refractory PM1 (particulate matter with an aerodynamic diameter da < 1 μm) mass. Secondary organic aerosol (SOA) is an important contributor to the OA and can be formed from biogenic and anthropogenic precursors. Here we present results from the characterization of SOA produced from the emissions of three different anthropogenic sources. SOA from a log wood burner, a Euro 2 diesel car and a two-stroke Euro 2 scooter were characterized with an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS) and compared to SOA from α-pinene. The emissions were sampled from the chimney/tailpipe by a heated inlet system and filtered before injection into a smog chamber. The gas phase emissions were irradiated by xenon arc lamps to initiate photo-chemistry which led to nucleation and subsequent particle growth by SOA production. Duplicate experiments were performed for each SOA type, with the averaged organic mass spectra in the m/z range 12-250 showing Pearson's r values >0.94 for the correlations between the different SOA types after 5 h of aging. High-resolution mass spectra (HR-MS) showed that the dominant peaks in the MS, m/z 43 and 44, are dominated by the oxygenated ions C2H3O+ and CO2+, respectively, similarly to the relatively fresh semi-volatile oxidized OA (SV-OOA) observed in the ambient aerosol. The atomic O : C ratios were found to be in the range of 0.25-0.55 with no major increase during the first 5 h of aging. On average, the diesel SOA showed the lowest O : C ratio followed by SOA from wood burning, α-pinene and the scooter emissions. Grouping the fragment ions based on their carbon number revealed that the SOA source with the highest O : C ratio had the largest fraction of small ions. Fragment ions containing up to 3 carbon atoms accounted for 66%, 68%, 72% and 76% of the organic spectrum of the SOA produced by the diesel car, wood burner, α-pinene and

  14. Determination of the bioaccessible fraction of metals in urban aerosol using simulated lung fluids

    NASA Astrophysics Data System (ADS)

    Coufalík, Pavel; Mikuška, Pavel; Matoušek, Tomáš; Večeřa, Zbyněk

    2016-09-01

    Determination of the bioaccessible fraction of metals in atmospheric aerosol is a significant issue with respect to air pollution in the urban environment. The aim of this work was to compare of metal bioaccessibility determined according to the extraction yields of six simulated lung fluids. Aerosol samples of the PM1 fraction were collected in Brno, Czech Republic. The total contents of Cd, Ce, Cr, Cu, Fe, Mn, Ni, Pb, V, and Zn in the samples were determined and their enrichment factors were calculated. The bioaccessible proportions of elements were determined by means of extraction in Gamble's solution, Gamble's solution with dipalmitoyl phosphatidyl choline (DPPC), artificial lysosomal fluid, saline, water, and in a newly proposed solution based on DPPC, referred to as "Simulated Alveoli Fluid" (SAF). The chemical composition and surface tension of the simulated lung fluids were the main parameters influencing extraction yields. Gamble's solutions and the newly designed solution of SAF exhibited the lowest extraction efficiency, and also had the lowest surface tensions. The bioaccessibility of particulate metals should be assessed by synthetic lung fluids with a low surface tension, which simulate better the behavior and composition of native lung surfactant. The bioaccessibility of metals in aerosol assessed by means of the extraction in water or artificial lysosomal fluid can be overestimated.

  15. Characterization of submicron aerosols during a serious pollution month in Beijing (2013) using an aerodyne high-resolution aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Zhang, J. K.; Sun, Y.; Liu, Z. R.; Ji, D. S.; Hu, B.; Liu, Q.; Wang, Y. S.

    2013-07-01

    In January 2013, Beijing experienced several serious haze events. To achieve a better understanding of the characteristics, sources and processes of aerosols during this month, an Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) was deployed at an urban site between 1 January and 1 February 2013 to obtain the size-resolved chemical composition of non-refractory submicron particles (NR-PM1). During this period, the mean measured NR-PM1 mass concentration was 87.4 μg m-3 and was composed of organics (49.8%), sulfate (21.4%), nitrate (14.6%), ammonium (10.4%), and chloride (3.8%). Moreover, inorganic matter, such as sulfate and nitrate comprised an increasing fraction of the NR-PM1 load as NR-PM1 loading increased, denoting their key roles in particulate pollution during this month. The average size distributions of the species were all dominated by an accumulation mode peaking at approximately 600 nm in vacuum aerodynamic diameter and organics characterized by an additional smaller size (∼200 nm). Elemental analyses showed that the average O/C, H/C, and N/C (molar ratio) of organic matter were 0.34, 1.44 and 0.015, respectively, corresponding to an OM/OC ratio (mass ratio of organic matter to organic carbon) of 1.60. Positive matrix factorization (PMF) analyses of the high-resolution organic mass spectral dataset differentiated the organic aerosol into four components, i.e., oxygenated organic aerosols (OOA), cooking-related (COA), nitrogen-containing (NOA) and hydrocarbon-like (HOA), which on average accounted for 40.0, 23.4, 18.1 and 18.5% of the total organic mass, respectively. Back trajectory clustering analyses indicated that the WNW air masses were associated with the highest NR-PM1 pollution during the campaign. Aerosol particles in southern air masses were especially rich in inorganic and oxidized organic species, whereas northern air masses contained a large fraction of primary species.

  16. Characterization of organic aerosols in Beijing using an aerodyne high-resolution aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Zhang, Junke; Wang, Yuesi; Huang, Xiaojuan; Liu, Zirui; Ji, Dongsheng; Sun, Yang

    2015-06-01

    Fine particle of organic aerosol (OA), mostly arising from pollution, are abundant in Beijing. To achieve a better understanding of the difference in OA in summer and autumn, a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS, Aerodyne Research Inc., USA) was deployed in urban Beijing in August and October 2012. The mean OA mass concentration in autumn was 30±30 μg m-3, which was higher than in summer (13±6.9 μg m-3). The elemental analysis found that OA was more aged in summer (oxygen-to-carbon (O/C) ratios were 0.41 and 0.32 for summer and autumn, respectively). Positive matrix factorization (PMF) analysis identified three and five components in summer and autumn, respectively. In summer, an oxygenated OA (OOA), a cooking-emission-related OA (COA), and a hydrocarbon-like OA (HOA) were indentified. Meanwhile, the OOA was separated into LV-OOA (low-volatility OOA) and SV-OOA (semi-volatile OOA); and in autumn, a nitrogen-containing OA (NOA) was also found. The SOA (secondary OA) was always the most important OA component, accounting for 55% of the OA in the two seasons. Back trajectory clustering analysis found that the origin of the air masses was more complex in summer. Southerly air masses in both seasons were associated with the highest OA loading, while northerly air masses were associated with the lowest OA loading. A preliminary study of OA components, especially the POA (primary OA), in different periods found that the HOA and COA all decreased during the National Day holiday period, and HOA decreased at weekends compared with weekdays.

  17. Bio-Aerosol Detection Using Mass Spectrometry: Public Health Applications

    SciTech Connect

    Ludvigson, L D

    2004-03-05

    I recently spent a summer as an intern at the Lawrence Livermore National Laboratory. I worked on a project involving the real-time, reagentless, single cell detection of aerosolized pathogens using a novel mass spectrometry approach called Bio-Aerosol Mass Spectrometry (BAMS). Based upon preliminary results showing the differentiation capabilities of BAMS, I would like to explore the development and use of this novel detection system in the context of both environmental and clinical sample pathogen detection. I would also like to explore the broader public health applications that a system such as BAMS might have in terms of infectious disease prevention and control. In order to appreciate the potential of this instrument, I will demonstrate the need for better pathogen detection methods, and outline the instrumentation, data analysis and preliminary results that lead me toward a desire to explore this technology further. I will also discuss potential experiments for the future along with possible problems that may be encountered along the way.

  18. Evolution of the gas mass fraction in galaxy clusters

    NASA Astrophysics Data System (ADS)

    Dvorkin, Irina; Rephaeli, Yoel

    2015-06-01

    The mass fraction of hot gas in clusters is a basic quantity whose level and dependence on the cluster mass and redshift are intimately linked to all cluster X-ray and Sunyayev-Zel'dovich measures. Modelling the evolution of the gas fraction is clearly a necessary ingredient in the description of the hierarchical growth of clusters through mergers of subclumps and mass accretion on the one hand, and the dispersal of gas from the cluster galaxies by tidal interactions, galactic winds and ram-pressure stripping on the other hand. A reasonably complete description of this evolution can only be given by very detailed hydrodynamical simulations, which are, however, resource-intensive and difficult to implement in the mapping of parameter space. A much more practical approach is the use of semi-analytic modelling that can be easily implemented to explore a wide range of parameters. We present first results from a simple model that describes the build-up of the gas mass fraction in clusters by following the overall impact of the above processes during the merger and accretion history of each cluster in the ensemble. Acceptable ranges for model parameters are deduced through comparison with results of X-ray observations. Basic implications of our work for modelling cluster statistical properties, and the use of these properties in joint cosmological data analyses, are discussed.

  19. In situ acidity and pH of size-fractionated aerosols during a recent smoke-haze episode in Southeast Asia.

    PubMed

    Behera, Sailesh N; Cheng, Jinping; Balasubramanian, Rajasekhar

    2015-10-01

    The characterization of aerosol acidity has received increased attention in recent years due to its influence on atmospheric visibility, climate change and human health. Distribution of water soluble inorganic (WSI) ions in 12 different size fractions of aerosols was investigated under two different atmospheric conditions (smoke-haze and non-haze periods) in 2012 using the Micro-Orifice Uniform Deposit Impactor (MOUDI) and nano-MOUDI for the first time in Singapore. To estimate the in situ acidity ([H(+)]Ins) and in situ aerosol pH (pHIS), the Aerosol Inorganic Model version-IV under deliquescent mode of airborne particles was used at prevailing ambient temperature and relative humidity. The study revealed an increase in the levels of airborne particulate matter (PM) mass and concentrations of WSI ions for all size fractions during the smoke-haze period, which was caused by the trans-boundary transport of biomass burning-impacted air masses from Indonesia. A bimodal distribution was observed for concentrations of SO4(2-), NO3(-), Cl(-), K(+) and Na(+), whereas concentrations of NH4(+), Ca(2+) and Mg(2+) showed a single mode distribution. The concentration of WSI ions in PM1.8 during the smoke-haze period increased by 3.8 (for SO4(2-)) to 10.5 (for K(+)) times more than those observed during the non-haze period. The pHIS were observed to be lower during the smoke-haze period than that during the non-haze period for all size fractions of PM, indicating that atmospheric aerosols were more acidic due to the influence of biomass burning emissions. The particles in the accumulation mode were more acidic than those in the coarse mode. PMID:25432456

  20. Mixing state of ambient aerosols in Nanjing city by single particle mass spectrometry

    NASA Astrophysics Data System (ADS)

    Wang, Honglei; An, Junlin; Shen, Lijuan; Zhu, Bin; Xia, Li; Duan, Qing; Zou, Jianan

    2016-05-01

    To investigate the mixing state and size-resolved aerosol in Nanjing, measurements were carried out for the period 14th January-1st February 2013 by using a Single Particle Aerosol Mass Spectrometer (SPAMS). A total of 10,864,766 particles were sized with vacuum aerodynamic diameter (dva) in the range of 0.2-2.0 μm. Of which, 1,989,725 particles were successfully ionized. Aerosol particles employed for analyzing SPAMS data utilized 96% of the hit particles to identify 5 main particle groups. The particle classes include: K-rich particles (K-CN, K-Nitrate, K-Sulfate and K-Secondary), sodium particles, ammonium particles, carbon-rich particles (OC, EC and OCEC) and heavy-metal particles (Fe-Secondary, Pb-Nitrate, Cu-Mn-Secondary and V-Secondary). EC was the largest contributor with a fraction of 21.78%, followed by K-Secondary (17.87%), K-Nitrate (12.68%) and K-CN (11.25%). High particle level and high RH (relative humidity) are two important factors decreasing visibility in Nanjing. Different particle classes have distinct extinction effects. It anti-correlated well with visibility for the K-secondary, sodium, ammonium, EC, Fe-Secondary and K-Nitrate particles. The proportion of EC particles at 0.65-1.4 μm was up to 25% on haze days and was below 10% on clean days.

  1. Mixing state of ambient aerosols in Nanjing city by single particle mass spectrometry

    NASA Astrophysics Data System (ADS)

    Wang, Honglei; An, Junlin; Shen, Lijuan; Zhu, Bin; Xia, Li; Duan, Qing; Zou, Jianan

    2016-05-01

    To investigate the mixing state and size-resolved aerosol in Nanjing, measurements were carried out for the period 14th January-1st February 2013 by using a Single Particle Aerosol Mass Spectrometer (SPAMS). A total of 10,864,766 particles were sized with vacuum aerodynamic diameter (dva) in the range of 0.2-2.0 μm. Of which, 1,989,725 particles were successfully ionized. Aerosol particles employed for analyzing SPAMS data utilized 96% of the hit particles to identify 5 main particle groups. The particle classes include: K-rich particles (K-CN, K-Nitrate, K-Sulfate and K-Secondary), sodium particles, ammonium particles, carbon-rich particles (OC, EC and OCEC) and heavy-metal particles (Fe-Secondary, Pb-Nitrate, Cu-Mn-Secondary and V-Secondary). EC was the largest contributor with a fraction of 21.78%, followed by K-Secondary (17.87%), K-Nitrate (12.68%) and K-CN (11.25%). High particle level and high RH (relative humidity) are two important factors decreasing visibility in Nanjing. Different particle classes have distinct extinction effects. It anti-correlated well with visibility for the K-secondary, sodium, ammonium, EC, Fe-Secondary and K-Nitrate particles. The proportion of EC particles at 0.65-1.4 μm was up to 25% on haze days and was below 10% on clean days.

  2. Low-energy ion implantation: Large mass fractionation of argon

    NASA Technical Reports Server (NTRS)

    Ponganis, K. V.; Graf, TH.; Marti, K.

    1993-01-01

    The isotropic signatures of noble gases in the atmospheres of the Earth and other planets are considerably evolved when compared to signatures observed in the solar wind. The mechanisms driving the evolution of planetary volatiles from original compositions in the solar accretion disk are currently poorly understood. Modeling of noble-gas compositional histories requires knowledge of fractionating processes that may have operated through the evolutionary stages. Since these gases are chemically inert, information on noble-gas fractionation processes can be used as probes. The importance of understanding these processes extends well beyond 'noble-gas planetology.' Trapped argon acquired by low-energy implantation (approximately less than 100 eV) into solids is strongly mass fractionated (approximately greater than or equal to 3 percent/amu). This has potential implications for the origin and evolution of terrestrial planet atmospheres.

  3. Aerosol Composition in the Los Angeles Basin Studied by High Resolution Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Hayes, P. L.; Ortega, A. M.; Cubison, M.; Hu, W.; Toohey, D. W.; Flynn, J. H.; Grossberg, N.; Lefer, B. L.; Alvarez, S. L.; Rappenglueck, B.; Allan, J. D.; Taylor, J.; Holloway, J. S.; Gilman, J. B.; Kuster, W. C.; De Gouw, J. A.; Massoli, P.; Zhang, X.; Weber, R.; Zhao, Y.; Cliff, S. S.; Wexler, A. S.; Isaacman, G. A.; Worton, D. R.; Kreisberg, N. M.; Hering, S. V.; Goldstein, A. H.; Jimenez, J. L.

    2011-12-01

    Atmospheric aerosols impact climate and health, but their sources and composition are poorly understood. To address this knowledge gap, a high-resolution aerosol mass spectrometer (AMS) and complementary instrumentation were deployed during the 2010 CalNex campaign to characterize aerosol composition in the Los Angeles (LA) area. Total mass concentrations as well as the species concentrations measured by the AMS compare well with most other instruments. Nitrate dominates in the mornings, but its concentration is reduced in the afternoon when organic aerosols (OA) increase and dominate. The diurnal variations in concentrations are strongly influenced by emission transport from the source-rich western basin. The average OA to enhanced CO ratio increases with photochemical age from 25 to 80 μg m-3 ppm-1, which indicates significant secondary OA (SOA) production and that a large majority of OA is secondary in aged air. The ratio values are similar to those from Mexico City as well as New England and the Mid-Atlantic States. Positive matrix factorization (PMF) is used to assess the concentrations of different OA components. The major OA classes are oxygenated OA (OOA, a surrogate for total SOA), and hydrocarbon-like OA (HOA, a surrogate for primary combustion OA). Several subclasses of OA are identified as well including diesel-influenced HOA (DI-HOA) and non-diesel HOA. DI-HOA exhibits low concentrations on Sundays consistent with the well-known weekday/weekend effect in LA. PMF analysis finds that OOA is 67% of the total OA concentration. A strong correlation between OOA and Ox (O3 + NO2) concentrations is observed with a slope of 0.15 that suggests the production of fresh SOA in Pasadena. Plotting the OA elemental ratios in a Van Krevelen diagram (H:C vs. O:C) yields a slope of -0.6, which is less steep than that observed in Riverside during the SOAR-2005 campaign. The difference in slopes may be attributed to the highly oxidized HOA present in Pasadena that is

  4. Exploring Atmospheric Aerosol Chemistry with Advanced High-Resolution Mass Spectrometry and Particle Imaging Methods

    NASA Astrophysics Data System (ADS)

    Nizkorodov, S.

    2014-12-01

    Physical and chemical complexity of atmospheric aerosols presents significant challenges both to experimentalists working on aerosol characterization and to modelers trying to parameterize critical aerosol properties. Multi-modal approaches that combine state-of-the-art experimental, theoretical, and modeling methods are becoming increasingly important in aerosol research. This presentation will discuss recent applications of unique high-resolution mass spectrometry and particle imaging tools developed at two Department of Energy's user facilities, the Environmental Molecular Science Laboratory (EMSL) and Advanced Light Source (ALS), to studies of molecular composition, photochemical aging, and properties of laboratory-generated and field aerosols. Specifically, this presentation will attempt to address the following questions: (a) how do NO2, SO2, and NH3 affect molecular level composition of anthropogenic aerosols?; (b) what factors determine viscosity/surface tension of organic aerosol particles?; (c) how does photolysis affect molecular composition and optical properties of organic aerosols?

  5. Combined observational and modeling based study of the relationship between aerosols and super-cooled cloud fraction

    NASA Astrophysics Data System (ADS)

    Storelvmo, T.; Lohmann, U.; Choi, Y.

    2011-12-01

    Recent observational and modeling studies indicate that aerosols may have a strong effect on Earth's energy budget via their influence on mixed-phase clouds. Global climate studies have predicted aerosol interaction with mixed-phase clouds to warm the current climate, but estimates are uncertain because mixed-phase cloud processes in GCMs are highly parameterized and have to date been poorly constrained by satellite data. Here, we present global and regional distributions of the frequency of supercooled cloud water and its link to aerosols from two global climate models (GCMs), compared to a new satellite data set. Both GCMs link ice formation at temperatures between -40 and 0 degrees C to the simulated concentrations of aerosols with ice nucleating ability (IN), assigning different freezing efficiencies to the different insoluble aerosol species (mineral dust, bio-aerosols and soot). Consequently, both models generally simulate an anti-correlation between aerosol abundance and supercooled liquid water in clouds, a finding that was recently qualitatively confirmed by satellite observations. By studying the relationship between aerosols and the supercooled cloud fraction (SCF) from the GCMs and from the NASA spaceborne lidar instrument CALIOP (cloud-aerosol lidar with orthogonal polarization), we get strong indications of how aerosols may influence mixed-phase clouds. Furthermore, based on the guidance from the satellite data, we perform global sensitivity simulations of the radiative effects associated with aerosol influence on mixed-phase clouds. We argue that with the new validation of SCF and its link to aerosols, GCM estimates of aerosol effects on climate via their influence on mixed-phase clouds may become more reliable.

  6. Estimation of aerosol mass scattering efficiencies under high mass loading: case study for the megacity of Shanghai, China.

    PubMed

    Cheng, Zhen; Jiang, Jingkun; Chen, Changhong; Gao, Jian; Wang, Shuxiao; Watson, John G; Wang, Hongli; Deng, Jianguo; Wang, Buying; Zhou, Min; Chow, Judith C; Pitchford, Marc L; Hao, Jiming

    2015-01-20

    Aerosol mass scattering efficiency (MSE), used for the scattering coefficient apportionment of aerosol species, is often studied under the condition of low aerosol mass loading in developed countries. Severe pollution episodes with high particle concentration frequently happened in eastern urban China in recent years. Based on synchronous measurement of aerosol physical, chemical, and optical properties at the megacity of Shanghai for two months during autumn 2012, we studied MSE characteristics at high aerosol mass loading. Their relationships with mass concentrations and size distributions were examined. It was found that MSE values from the original US IMPROVE algorithm could not represent the actual aerosol characteristics in eastern China. It results in an underestimation of the measured ambient scattering coefficient by 36%. MSE values in Shanghai were estimated to be 3.5 ± 0.55 m(2)/g for ammonia sulfate, 4.3 ± 0.63 m(2)/g for ammonia nitrate, and 4.5 ± 0.73 m(2)/g for organic matter, respectively. MSEs for three components increased rapidly with increasing mass concentration in low aerosol mass loading, then kept at a stable level after a threshold mass concentration of 12–24 μg/m(3). During severe pollution episodes, particle growth from an initial peak diameter of 200–300 nm to a peak diameter of 500–600 nm accounts for the rapid increase in MSEs at high aerosol mass loading, that is, particle diameter becomes closer to the wavelength of visible lights. This study provides insights of aerosol scattering properties at high aerosol concentrations and implies the necessity of MSE localization for extinction apportionment, especially for the polluted regions. PMID:25495050

  7. Investigation of formation and ageing of biogenic secondary aerosols by soft ionization aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Müller, Lars; Reinnig, Marc-Christopher; Vogel, Alexander; Mentel, Thomas; Tillmann, Ralf; Schlosser, E.; Wahner, Andreas; Donahue, Neil; Saathoff, Harald; Hoffmann, Thorsten

    2010-05-01

    The knowledge of the chemical composition of secondary organic aerosol is one essential key to understand the significance and fate of SOA in the atmosphere. However, the chemical evolution of SOA, from the very first condensing/nucleating molecules to the final oxidation products is still insufficiently understood and object of current research [1-3]. Consequently, the formation and photochemical ageing of secondary organic aerosol (SOA) was investigated in a series of reaction chamber experiments by applying on-line aerosol mass spectrometry (atmospheric pressure chemical ionization mass spectrometry (APCI/MS)) as well as off-line high performance liquid chromatography mass spectrometry (HPLC-MS). In a set of experiments, performed in the large outdoor reaction chamber SAPHIR (Jülich, Germany), SOA was generated from a boreal mixture of biogenic VOCs. During a two-day experiment the generated biogenic SOA was exposed to OH-radicals and the temporal evolution of the chemical composition was characterized. The applied on-line MS method not only provides highly time resolved chemical information (such as an AMS) but also allows molecular identification/quantification of specific marker compounds. Several first and higher generation BSOA products were identified. Among the higher generation products, especially a tricarboxylic acid (3-methyl-1,2,3-butanetricarboxylic acid) [2] was observed as an eye-catching oxidative processing marker. A more detailed investigation of hydroxyl radical induced SOA aging at the AIDA chamber facility in Karlsruhe, again using terpenes as SOA precursors, clearly showed that the formation of the tricarboxylic acid takes place in the gas phase by the reaction of semivolatile first generation products and hydroxyl radicals. Actually, there were no indications for OH induced oxidation of compounds in the condensed phase. The consequences of these results will be discussed in the contribution. 1. Rudich, Y., N.M. Donahue, and T.F. Mentel

  8. Dynamics of Particle Size on Inhalation of Environmental Aerosol and Impact on Deposition Fraction.

    PubMed

    Haddrell, Allen E; Davies, James F; Reid, Jonathan P

    2015-12-15

    Inhalation of elevated levels of particulate air pollution has been shown to elicit the onset of adverse health effects in humans, where the magnitude of the response is a product of where in the lung the particulate dose is delivered. At any point in time during inhalation the depositional flux of the aerosol is a function of the radius of the droplet, thus a detailed understanding of the rate and magnitude of the mass flux of water to the droplet during inhalation is crucial. In this study, we assess the impact of aerosol hygroscopicity on deposited dose through the inclusion of a detailed treatment of the mass flux of water to account for the dynamics of particle size in a modified version of the standard International Commission on Radiological Protection (ICRP) whole lung deposition model. The ability to account for the role of the relative humidity (RH) of the aerosol prior to, and during, inhalation on the deposition pattern is explored, and found to have a significant effect on the deposition pattern. The model is verified by comparison to previously published measurements, and used to demonstrate that ambient RH affects where in the lung indoor particulate air pollution is delivered. PMID:26568475

  9. In situ vertical profiles of aerosol extinction, mass, and composition over the southeast United States during SENEX and SEAC4RS: observations of a modest aerosol enhancement aloft

    NASA Astrophysics Data System (ADS)

    Wagner, N. L.; Brock, C. A.; Angevine, W. M.; Beyersdorf, A.; Campuzano-Jost, P.; Day, D.; de Gouw, J. A.; Diskin, G. S.; Gordon, T. D.; Graus, M. G.; Holloway, J. S.; Huey, G.; Jimenez, J. L.; Lack, D. A.; Liao, J.; Liu, X.; Markovic, M. Z.; Middlebrook, A. M.; Mikoviny, T.; Peischl, J.; Perring, A. E.; Richardson, M. S.; Ryerson, T. B.; Schwarz, J. P.; Warneke, C.; Welti, A.; Wisthaler, A.; Ziemba, L. D.; Murphy, D. M.

    2015-06-01

    Vertical profiles of submicron aerosol from in situ aircraft-based measurements were used to construct aggregate profiles of chemical, microphysical, and optical properties. These vertical profiles were collected over the southeastern United States (SEUS) during the summer of 2013 as part of two separate field studies: the Southeast Nexus (SENEX) study and the Study of Emissions and Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys (SEAC4RS). Shallow cumulus convection was observed during many profiles. These conditions enhance vertical transport of trace gases and aerosol and create a cloudy transition layer on top of the sub-cloud mixed layer. The trace gas and aerosol concentrations in the transition layer were modeled as a mixture with contributions from the mixed layer below and the free troposphere above. The amount of vertical mixing, or entrainment of air from the free troposphere, was quantified using the observed mixing ratio of carbon monoxide (CO). Although the median aerosol mass, extinction, and volume decreased with altitude in the transition layer, they were ~10 % larger than expected from vertical mixing alone. This enhancement was likely due to secondary aerosol formation in the transition layer. Although the transition layer enhancements of the particulate sulfate and organic aerosol (OA) were both similar in magnitude, only the enhancement of sulfate was statistically significant. The column integrated extinction, or aerosol optical depth (AOD), was calculated for each individual profile, and the transition layer enhancement of extinction typically contributed less than 10 % to the total AOD. Our measurements and analysis were motivated by two recent studies that have hypothesized an enhanced layer of secondary aerosol aloft to explain the summertime enhancement of AOD (2-3 times greater than winter) over the southeastern United States. The first study attributes the layer aloft to secondary organic aerosol (SOA) while

  10. Analysis of Nitrogen Containing Organic Compounds in Biomass Burning Aerosols Using High Resolution Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Laskin, A.; Smith, J. S.; Laskin, J.

    2009-05-01

    Chemical characterization of atmospheric aerosols presents a serious analytical challenge because of the complexity of particulate matter analyte composed of a large number of compounds with a wide range of molecular structures, physico-chemical properties, and reactivity. In this study the chemical composition of the nitrogen containing organic (NOC) constituents of biomass burning aerosol (BBA) samples is characterized by high-resolution electrospray ionization mass spectrometry (ESI/MS). Accurate mass measurements combined with MS/MS fragmentation experiments of selected ions were used to assign molecular structures to individual NOC species. Our results indicate that N-heterocyclic alkaloid compounds - species naturally produced by plants and living organisms - comprise a substantial fraction of NOC in BBA samples collected from test burns of five biomass fuels. High abundance of alkaloids in test burns of ponderosa pine - a widespread tree in the western U.S. areas frequently affected by large scale fires - suggests that N-heterocyclic alkaloids in BBA may play a significant role in dry and wet deposition of fixed nitrogen in this region. Atmospheric processing and chemical transformations of alkaloids in the particulate phase will be discussed.

  11. The Effect of Solvent on the Analysis of Secondary Organic Aerosol Using Electrospray Ionization Mass Spectrometry

    SciTech Connect

    Bateman, Adam P.; Walser, Maggie L.; Dessiaterik, Yury; Laskin, Julia; Laskin, Alexander; Nizkorodov, Serguei

    2008-08-29

    Solvent-analyte reactions in organic aerosol (OA) extracts prepared for analysis by electrospray ionization mass spectrometry (ESI-MS) were examined. Secondary organic aerosol (SOA) produced by ozonation of d-limonene as well as several test organic chemicals with functional groups typical for OA constituents were dissolved and stored in methanol, d3-methanol, acetonitrile, and d3-acetonitrile to investigate the extent and relative rates of reactions between analyte and solvent. High resolution ESI-MS showed that reactions of carbonyls with methanol produce significant amounts of hemiacetals and acetals on time scales ranging from several minutes to several days, with the reaction rates increasing in acidified solutions. Carboxylic acid groups were observed to react with methanol resulting in the formation of esters. In contrast, acetonitrile extracts showed no evidence of reactions with analyte molecules, suggesting that acetonitrile is the preferred solvent for SOA extraction. The use of solvent-analyte reactivity as an analytical chemistry tool for the improved characterization of functional groups in complex organic mixtures was also demonstrated. Direct comparison between ESI mass spectra of the same SOA samples extracted in reactive (methanol) versus non-reactive (acetonitrile) solvents was used to estimate the relative fractions of ketones (≥38%), aldehydes (≥6%), and carboxylic acids (≥55%) in d-limonene SOA.

  12. Microbial mass-dependent fractionation of chromium isotopes

    USGS Publications Warehouse

    Sikora, E.R.; Johnson, T.M.; Bullen, T.D.

    2008-01-01

    Mass-dependent fractionation of Cr isotopes occurs during dissimilatory Cr(VI) reduction by Shewanella oneidensis strain MR-1. Cells suspended in a simple buffer solution, with various concentrations of lactate or formate added as electron donor, reduced 5 or 10 ??M Cr(VI) to Cr(III) over days to weeks. In all nine batch experiments, 53Cr/52Cr ratios of the unreacted Cr(VI) increased as reduction proceeded. In eight experiments covering a range of added donor concentrations up to 100 ??M, isotopic fractionation factors were nearly invariant, ranging from 1.0040 to 1.0045, with a mean value somewhat larger than that previously reported for abiotic Cr(VI) reduction (1.0034). One experiment containing much greater donor concentration (10 mM lactate) reduced Cr(VI) much faster and exhibited a lesser fractionation factor (1.0018). These results indicate that 53Cr/52Cr measurements should be effective as indicators of Cr(VI) reduction, either bacterial or abiotic. However, variability in the fractionation factor is poorly constrained and should be studied for a variety of microbial and abiotic reduction pathways. ?? 2008 Elsevier Ltd.

  13. Highly fractionated mass loss from the atmosphere of Pluto

    NASA Astrophysics Data System (ADS)

    Yen, Chien-Chang; Taam, Ronald E.; Liang, Mao-Chang

    2014-11-01

    Molecules can escape readily from the atmosphere of Pluto. Under the framework of hydrodynamic approximation, it was generally accepted that the process produced rather small isotopic fractionation. Here, we show that the escape highly fractionates the isotopic composition of nitrogen. The process preferentially selects lighter species, with an escape probability a factor of ~3 higher for the lighter isotopologue. The validity of the approach may be testable if the isotopic composition of the outer most regions can be measured. The property of the selection can significantly modify the isotopic composition of the atmosphere, leaving the present-day atmosphere isotopically heavier than the ancient one. This also impacts the current view of the evolution of planetary atmospheres. Venus, for example, may not need that much mass loss, in order to explain the current D/H ratio.

  14. Determination of solid mass fraction in partially frozen hydrocarbon fuels

    NASA Technical Reports Server (NTRS)

    Cotterell, E. M.; Mossadegh, R.; Bruce, A. J.; Moynihan, C. T.

    1986-01-01

    Filtration procedures alone are insufficient to determine the amounts of crystalline solid in a partially frozen hydrocarbon distillate fraction. This is due to the nature of the solidification process by which a large amount of liquid becomes entrapped within an interconnected crystalline structure. A technique has been developed to supplement filtration methods with an independent determination of the amount of liquid in the precipitate thereby revealing the actual value of mass percent crystalline solid, %S. A non-crystallizing dye is injected into the fuel and used as a tracer during the filtration. The relative concentrations of the dye in the filtrate and precipitate fractions is subsequently detected by a spectrophotometric comparison. The filtration apparatus was assembled so that the temperature of the sample is recorded immediately above the filter. Also, a second method of calculation has been established which allows significant reduction in test time while retaining acceptable accuracy of results. Data have been obtained for eight different kerosene range hydrocarbon fuels.

  15. Preliminary Results of Aerosol Chemical Composition Measurements in the Gulf of Maine with an Aerosol Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Middlebrook, A. M.; Canagaratna, M. R.; Worsnop, D. R.

    2002-12-01

    The New England Air Quality Study is a multi-institutional research project to improve understanding of the atmospheric processes that control the production and distribution of air pollutants in the New England region. During July-August, 2002 a large, collaborative, intensive period of atmospheric measurement and model comparisons took place. As part of this study, an Aerosol Mass Spectrometer (AMS) was deployed aboard the NOAA ship RONALD H. BROWN in the Gulf of Maine. The AMS measures semi-volatile components of aerosol particles with aerodynamic diameters between roughly 40 and 1500 nm. During this study, the AMS collected 2-minute averaged particle mass spectra as well as speciated organic, sulfate, and nitrate size distributions. Sodium chloride, sodium sulfate, and sodium nitrate components of the aerosol, which are relatively non-volatile at the AMS heater temperature, were not detected with the AMS. A wide variety of air masses were sampled during the intensive period, including clean marine, clean continental, and polluted continental air masses. In general, the volatile particle composition was mostly organic and sulfate with lesser amounts of nitrate. Furthermore, particle mass loadings typically peaked around 400-600 nm in aerodynamic diameter. Several events with high aerosol organic, sulfate, and/or nitrate mass loadings were observed and the atmospheric processes that cause them will be discussed.

  16. Characterization and source apportionment of submicron aerosol with aerosol mass spectrometer during the PRIDE-PRD 2006 campaign

    NASA Astrophysics Data System (ADS)

    Xiao, R.; Takegawa, N.; Zheng, M.; Kondo, Y.; Miyazaki, Y.; Miyakawa, T.; Hu, M.; Shao, M.; Zeng, L.; Gong, Y.; Lu, K.; Deng, Z.; Zhao, Y.; Zhang, Y. H.

    2011-01-01

    Size-resolved chemical compositions of non-refractory submicron aerosol were measured using an Aerodyne quadrupole aerosol mass spectrometer (Q-AMS) at the rural site Back Garden (BG), located ~50 km northwest of Guangzhou in July 2006. This paper characterized the submicron aerosol particles of regional air pollution in Pearl River Delta (PRD) in the Southern China. Organics and sulfate dominated the submicron aerosol compositions, with average mass concentrations of 11.8±8.4 μg m-3 and 13.5±8.7 μg m-3, respectively. Unlike other air masses, the air masses originated from Southeast-South and passing through the PRD urban areas exhibited distinct bimodal size distribution characteristics for both organics and sulfate: the first mode peaked at vacuum aerodynamic diameters (Dva)~200 nm and the second mode occurred at Dva from 300-700 nm. With the information from AMS, it was found from this study that the first mode of organics in PRD regional air masses was contributed by both secondary organic aerosol formation and combustion-related emissions, which is different from most findings in other urban areas (first mode of organics primarily from combustion-related emissions). The analysis of AMS mass spectra data by positive matrix factorization (PMF) model identified three sources of submicron organic aerosol including hydrocarbon-like organic aerosol (HOA), low volatility oxygenated organic aerosol (LV-OOA) and semi-volatile oxygenated organic aerosol (SV-OOA). The strong correlation between HOA and EC indicated primary combustion emissions as the major source of HOA while a close correlation between SV-OOA and semi-volatile secondary species nitrate as well as between LV-OOA and nonvolatile secondary species sulfate suggested secondary aerosol formation as the major source of SV-OOA and LV-OOA at the BG site. However, LV-OOA was more aged than SV-OOA as its spectra was highly correlated with the reference spectra of fulvic acid, an indicator of aged and

  17. Characterization and source apportionment of submicron aerosol with aerosol mass spectrometer during the PRIDE-PRD 2006 campaign

    NASA Astrophysics Data System (ADS)

    Xiao, R.; Takegawa, N.; Zheng, M.; Kondo, Y.; Miyazaki, Y.; Miyakawa, T.; Hu, M.; Shao, M.; Zeng, L.; Gong, Y.; Lu, K.; Deng, Z.; Zhao, Y.; Zhang, Y. H.

    2011-07-01

    Size-resolved chemical compositions of non-refractory submicron aerosol were measured using an Aerodyne quadrupole aerosol mass spectrometer (Q-AMS) at the rural site Back Garden (BG), located ~50 km northwest of Guangzhou in July 2006. This paper characterized the submicron aerosol particles of regional air pollution in Pearl River Delta (PRD) in the southern China. Organics and sulfate dominated the submicron aerosol compositions, with average mass concentrations of 11.8 ± 8.4 μg m-3 and 13.5 ± 8.7 μg m-3, respectively. Unlike other air masses, the air masses originated from Southeast-South and passing through the PRD urban areas exhibited distinct bimodal size distribution characteristics for both organics and sulfate: the first mode peaked at vacuum aerodynamic diameters (Dva) ∼200 nm and the second mode occurred at Dva from 300-700 nm. With the information from AMS, it was found from this study that the first mode of organics in PRD regional air masses was contributed by both secondary organic aerosol formation and combustion-related emissions, which is different from most findings in other urban areas (first mode of organics primarily from combustion-related emissions). The analysis of AMS mass spectra data by positive matrix factorization (PMF) model identified three sources of submicron organic aerosol including hydrocarbon-like organic aerosol (HOA), low volatility oxygenated organic aerosol (LV-OOA) and semi-volatile oxygenated organic aerosol (SV-OOA). The strong correlation between HOA and EC indicated primary combustion emissions as the major source of HOA while a close correlation between SV-OOA and semi-volatile secondary species nitrate as well as between LV-OOA and nonvolatile secondary species sulfate suggested secondary aerosol formation as the major source of SV-OOA and LV-OOA at the BG site. However, LV-OOA was more aged than SV-OOA as its spectra was highly correlated with the reference spectra of fulvic acid, an indicator of aged and

  18. Mass fractionation of the lunar surface by solar wind sputtering

    NASA Technical Reports Server (NTRS)

    Switkowski, Z. E.; Haff, P. K.; Tombrello, T. A.; Burnett, D. S.

    1977-01-01

    An investigation is conducted concerning the mass-fractionation effects produced in connection with the bombardment of the moon by the solar wind. Most of the material ejected by sputtering escapes the moon's gravity, but some returning matter settles back onto the lunar surface. This material, which is somewhat richer in heavier atoms than the starting surface, is incorporated into the heavily radiation-damaged outer surfaces of grains. The investigation indicates that sputtering of the lunar surface by the solar wind will give rise to significant surface heavy atom enrichments if the grain surfaces are allowed to come into sputtering equilibrium.

  19. Mass analysis of charged aerosol particles in NLC and PMSE during the ECOMA/MASS campaign

    NASA Astrophysics Data System (ADS)

    Robertson, S.; Horányi, M.; Knappmiller, S.; Sternovsky, Z.; Holzworth, R.; Shimogawa, M.; Friedrich, M.; Torkar, K.; Gumbel, J.; Megner, L.; Baumgarten, G.; Latteck, R.; Rapp, M.; Hoppe, U.-P.; Hervig, M. E.

    2009-03-01

    MASS (Mesospheric Aerosol Sampling Spectrometer) is a multichannel mass spectrometer for charged aerosol particles, which was flown from the Andøya Rocket Range, Norway, through NLC and PMSE on 3 August 2007 and through PMSE on 6 August 2007. The eight-channel analyzers provided for the first time simultaneous measurements of the charge density residing on aerosol particles in four mass ranges, corresponding to ice particles with radii <0.5 nm (including ions), 0.5-1 nm, 1-2 nm, and >3 nm (approximately). Positive and negative particles were recorded on separate channels. Faraday rotation measurements provided electron density and a means of checking charge density measurements made by the spectrometer. Additional complementary measurements were made by rocket-borne dust impact detectors, electric field booms, a photometer and ground-based radar and lidar. The MASS data from the first flight showed negative charge number densities of 1500-3000 cm-3 for particles with radii >3 nm from 83-88 km approximately coincident with PMSE observed by the ALWIN radar and NLC observed by the ALOMAR lidar. For particles in the 1-2 nm range, number densities of positive and negative charge were similar in magnitude (~2000 cm-3) and for smaller particles, 0.5-1 nm in radius, positive charge was dominant. The occurrence of positive charge on the aerosol particles of the smallest size and predominately negative charge on the particles of largest size suggests that nucleation occurs on positive condensation nuclei and is followed by collection of negative charge during subsequent growth to larger size. Faraday rotation measurements show a bite-out in electron density that increases the time for positive aerosol particles to be neutralized and charged negatively. The larger particles (>3 nm) are observed throughout the NLC region, 83-88 km, and the smaller particles are observed primarily at the high end of the range, 86-88 km. The second flight into PMSE alone at 84-88 km, found only

  20. Highly time-resolved urban aerosol characteristics during springtime in Yangtze River Delta, China: insights from soot particle aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Wang, Junfeng; Ge, Xinlei; Chen, Yanfang; Shen, Yafei; Zhang, Qi; Sun, Yele; Xu, Jianzhong; Ge, Shun; Yu, Huan; Chen, Mindong

    2016-07-01

    In this work, the Aerodyne soot particle - aerosol mass spectrometer (SP-AMS) was deployed for the first time during the spring of 2015 in urban Nanjing, a megacity in the Yangtze River Delta (YRD) of China, for online characterization of the submicron aerosols (PM1). The SP-AMS enables real-time and fast quantification of refractory black carbon (rBC) simultaneously with other non-refractory species (ammonium, sulfate, nitrate, chloride, and organics). The average PM1 concentration was found to be 28.2 µg m-3, with organics (45 %) as the most abundant component, following by sulfate (19.3 %), nitrate (13.6 %), ammonium (11.1 %), rBC (9.7 %), and chloride (1.3 %). These PM1 species together can reconstruct ˜ 44 % of the light extinction during this campaign based on the IMPROVE method. Chemically resolved mass-based size distributions revealed that small particles especially ultrafine ones (< 100 nm vacuum aerodynamic diameter) were dominated by organics and rBC, while large particles had significant contributions from secondary inorganic species. Source apportionment of organic aerosols (OA) yielded four OA subcomponents, including hydrocarbon-like OA (HOA), cooking-related OA (COA), semi-volatile oxygenated OA (SV-OOA), and low-volatility oxygenated OA (LV-OOA). Overall, secondary organic aerosol (SOA, equal to the sum of SV-OOA and LV-OOA) dominated the total OA mass (55.5 %), but primary organic aerosol (POA, equal to the sum of HOA and COA) can outweigh SOA in the early morning and evening due to enhanced human activities. High OA concentrations were often associated with high mass fractions of POA and rBC, indicating the important role of anthropogenic emissions during heavy pollution events. The diurnal cycles of nitrate, chloride, and SV-OOA both showed good anti-correlations with air temperatures, suggesting their variations were likely driven by thermodynamic equilibria and gas-to-particle partitioning. On the other hand, in contrast to other species

  1. Concentration Effects and Ion Properties Controlling the Fractionation of Halides during Aerosol Formation

    NASA Technical Reports Server (NTRS)

    Guzman, Marcelo I.; Athalye, Richa R.; Rodriguez, Jose M.

    2012-01-01

    During the aerosolization process at the sea surface, halides are incorporated into aerosol droplets, where they may play an important role in tropospheric ozone chemistry. Although this process may significantly contribute to the formation of reactive gas phase molecular halogens, little is known about the environmental factors that control how halides selectively accumulate at the air-water interface. In this study, the production of sea spray aerosol is simulated using electrospray ionization (ESI) of 100 nM equimolar solutions of NaCl, NaBr, NaI, NaNO2, NaNO3, NaClO4, and NaIO4. The microdroplets generated are analyzed by mass spectrometry to study the comparative enrichment of anions (f (Isub x-)) and their correlation with ion properties. Although no correlation exists between f (sub x-) and the limiting equivalent ionic conductivity, the correlation coefficient of the linear fit with the size of the anions R(sub x-), dehydration free-energy ?Gdehyd, and polarizability alpha, follows the order: (R(sub x-)(exp -2)) > (R(sub x-)(exp -1)) >(R(sub x-) > delta G(sub dehyd) > alpha. The same pure physical process is observed in H2O and D2O. The factor f (sub x-) does not change with pH (6.8-8.6), counterion (Li+, Na+, K+, and Cs+) substitution effects, or solvent polarity changes in methanol - and ethanol-water mixtures (0 <= xH2O <= 1). Sodium polysorbate 20 surfactant is used to modify the structure of the interface. Despite the observed enrichment of I- on the air-water interface of equimolar solutions, our results of seawater mimic samples agree with a model in which the interfacial composition is increasingly enriched in I- < Br- < Cl- over the oceanic boundary layer due to concentration effects in sea spray aerosol formation.

  2. Mass-Independent Fractionation of Mercury in Hydrothermal Systems

    NASA Astrophysics Data System (ADS)

    Sherman, L. S.; Blum, J. D.; Nordstrom, D. K.; McCleskey, R. B.; Barkay, T.; Vetriani, C.

    2008-12-01

    Experimental results indicate that mass-independent fractionation (MIF) of mercury occurs during both photochemical reduction of Hg2+ and photochemical demethylation of methyl-mercury. In aqueous systems, the photochemical reduction of Hg2+aq to Hg0aq and subsequent evasion of Hg0g preferentially retains the odd mass isotopes of Hg in the aqueous phase and releases the even mass isotopes of Hg in Hg0g. MIF of Hg has been observed recently in marine and freshwater fish, soils, peat, mosses and sediments. We investigated Hg in modern volcanic-hydrothermal systems to evaluate whether major earth reservoirs carry a MIF signature. Hydrothermal systems driven by mantle-derived volcanism are a major natural source of Hg to the atmosphere and may represent the isotopic composition of deep geological reservoirs. We analyzed fluid and siliceous sinter samples from hot springs in the Yellowstone Plateau volcanic field and vent chimney precipitates from the Guaymas Basin sea-floor rift. In all of the analyzed fluid and sinter samples from Ojo Caliente hot spring in Yellowstone, we observed a small but significant positive MIF (Δ199Hg = 0.13‰ ± 0.06‰, 2SD). No significant MIF was measured in any of the sea-floor rift samples from Guaymas Basin. In Ojo Caliente, Hg is both lost from the fluids and fractionated mass-dependently along a flow path from the hot spring vent to the outflow channel. We suggest that Hg loss and mass-dependent fractionation occur in this system due to volatilization of Hg0aq to Hg0g. In contrast, because all of the samples measured from Ojo Caliente exhibited approximately the same degree of MIF, it is not likely that measurable photochemical reduction of Hg is occurring in this system on the short timescale (i.e., minutes) of fluid discharge. Instead, we suggest that either (1) some portion of the Hg in the system was photochemically reduced at the earth's surface in the past and transported back to the subsurface (perhaps by groundwater

  3. Direct measurements of mass-specific optical cross sections of single-component aerosol mixtures.

    PubMed

    Radney, James G; Ma, Xiaofei; Gillis, Keith A; Zachariah, Michael R; Hodges, Joseph T; Zangmeister, Christopher D

    2013-09-01

    The optical properties of atmospheric aerosols vary widely, being dependent upon particle composition, morphology, and mixing state. This diversity and complexity of aerosols motivates measurement techniques that can discriminate and quantify a variety of single- and multicomponent aerosols that are both internally and externally mixed. Here, we present a new combination of techniques to directly measure the mass-specific extinction and absorption cross sections of laboratory-generated aerosols that are relevant to atmospheric studies. Our approach employs a tandem differential mobility analyzer, an aerosol particle mass analyzer, cavity ring-down and photoacoustic spectrometers, and a condensation particle counter. This suite of instruments enables measurement of aerosol particle size, mass, extinction and absorption coefficients, and aerosol number density, respectively. Taken together, these observables yield the mass-specific extinction and absorption cross sections without the need to model particle morphology or account for sample collection artifacts. Here we demonstrate the technique in a set of case studies which involve complete separation of aerosol by charge, separation of an external mixture by mass, and discrimination between particle types by effective density and single-scattering albedo. PMID:23875772

  4. Contribution of isoprene-derived organosulfates to free tropospheric aerosol mass.

    PubMed

    Froyd, K D; Murphy, S M; Murphy, D M; de Gouw, J A; Eddingsaas, N C; Wennberg, P O

    2010-12-14

    Recent laboratory studies have demonstrated that isoprene oxidation products can partition to atmospheric aerosols by reacting with condensed phase sulfuric acid, forming low-volatility organosulfate compounds. We have identified organosulfate compounds in free tropospheric aerosols by single particle mass spectrometry during several airborne field campaigns. One of these organosulfates is identified as the sulfate ester of IEPOX, a second generation oxidation product of isoprene. The patterns of IEPOX sulfate ester in ambient data generally followed the aerosol acidity and NO(x) dependence established by laboratory studies. Detection of the IEPOX sulfate ester was most sensitive using reduced ionization laser power, when it was observed in up to 80% of particles in the tropical free troposphere. Based on laboratory mass calibrations, IEPOX added > 0.4% to tropospheric aerosol mass in the remote tropics and up to 20% in regions downwind of isoprene sources. In the southeastern United States, when acidic aerosol was exposed to fresh isoprene emissions, accumulation of IEPOX increased aerosol mass by up to 3%. The IEPOX sulfate ester is therefore one of the most abundant single organic compounds measured in atmospheric aerosol. Our data show that acidity-dependent IEPOX uptake is a mechanism by which anthropogenic SO(2) and marine dimethyl sulfide emissions generate secondary biogenic aerosol mass throughout the troposphere. PMID:21098310

  5. Characteristics of aerosols and mass closure study at two WMO GAW regional background stations in eastern China

    NASA Astrophysics Data System (ADS)

    Yan, Peng; Zhang, Renjian; Huan, Ning; Zhou, Xiuji; Zhang, Yangmei; Zhou, Huaigang; Zhang, Leiming

    2012-12-01

    In the summer and winter of 2004 and 2005, size-segregated atmospheric aerosols were sampled with modified Andersen KA200 Multi-stage impactor at two regional background stations in the eastern China, the Shangdianzi station (SDZ) in the suburb of Beijing and the Lin'An station (LA) in the Yangtze river delta region, both are WMO Global Atmospheric Watch station, which represent the regional background of air pollutions of the two rapid developing economical zone of China, the Yangtze River Delta region (YRD) and Beijing-Tianjin region. The aerosol mass size distributions, ionic compositions, organic and elemental carbon (OC and EC), and elemental components were analyzed. The mass concentrations for TSP (total suspend particle), PM11 (aerodynamic diameter less than 11 μm), and PM2.1 (aerodynamic diameter less than 2.1 μm) at both sites showed obviously different between the winter and summer, with higher mass concentrations measured in the winter time. All seasonal mean mass concentrations of PM2.1 accounted for over 50% of PM11 at both sites. The aerosol mass closure study indicated that the total mass concentration reconstructed from the aerosol chemical composition agreed well with the measured gravimetric mass at the two stations. The fine aerosol particles at the two stations were composed mainly of sulfate and organic matter. In the summer, more than half of the PM2.1 mass was sulfate, suggesting a dominant contribution of secondary aerosol to the fine particles in these two regions. In the winter, the contribution of nitrate to the fine particles increased significantly due to the lower volatile losses under the cold weather. The proportions of soil type components in the PM2.1 showed similar magnitude in the winter and summer at Lin'An station but significant seasonal differences with higher fractions in the winter at Shangdianzi station. On average EC accounted for about 2%-6% of the fine particle mass (PM2.1) at both sites with proportionally lower EC

  6. Detection of brake wear aerosols by aerosol time-of-flight mass spectrometry

    NASA Astrophysics Data System (ADS)

    Beddows, D. C. S.; Dall'Osto, M.; Olatunbosun, O. A.; Harrison, Roy M.

    2016-03-01

    Brake dust particles were characterised using an Aerosol Time-of-Flight Mass Spectrometer (ATOFMS) operated using two inlet configurations, namely the aerodynamic lens (AFL) inlet and countersunk nozzle inlet. Laboratory studies show that dust particles are characterised by mass spectra containing ions deriving from Fe and Ba and although highly correlated to each other, the Fe and Ba signals were mostly detected using the nozzle inlet with relatively high laser desorption energies. When using the AFL, only [56Fe] and [-88FeO2] ions were observed in brake dust spectra generated using lower laser desorption pulse energies, and only above 0.75 mJ was the [138Ba] ion detected. When used with the preferred nozzle inlet configuration, the [-88FeO2] peak was considered to be the more reliable tracer peak, because it is not present in other types of dust (mineral, tyre, Saharan etc). As shown by the comparison with ambient data from a number of locations, the aerodynamic lens is not as efficient in detecting brake wear particles, with less than 1% of sampled particles attributed to brake wear. Five field campaigns within Birmingham (background, roadside (3) and road tunnel) used the nozzle inlet and showed that dust particles (crustal and road) accounted for between 3.1 and 65.9% of the particles detected, with the remaining particles being made up from varying percentages of other constituents.

  7. High-Resolution Electrospray Ionization Mass Spectrometry Analysis of Water- Soluble Organic Aerosols Collected with a Particle into Liquid Sampler

    SciTech Connect

    Bateman, Adam P.; Nizkorodov, Serguei; Laskin, Julia; Laskin, Alexander

    2010-10-01

    This work demonstrates the utility of a particle-into-liquid sampler (PILS) a technique traditionally used for identification of inorganic ions present in ambient or laboratory aerosols for the analysis of water soluble organic aerosol (OA) using high resolution electrospray ionization mass spectrometry (HR ESI-MS). Secondary organic aerosol (SOA) was produced from 0.5 ppm mixing ratios of limonene and ozone in a 5 m3 Teflon chamber. SOA was collected simultaneously using a traditional filter sampler and a PILS. The filter samples were later extracted with either water or acetonitrile, while the aqueous PILS samples were analyzed directly. In terms of peak intensities, types of detectable compounds, average O:C ratios, and organic mass to organic carbon ratios, the resulting high resolution mass spectra were essentially identical for the PILS and filter based samples. SOA compounds extracted from both filter/acetonitrile extraction and PILS/water extraction accounted for >95% of the total ion current in ESI mass spectra. This similarity was attributed to high solubility of limonene SOA in water. In contrast, significant differences in detected ions and peak abundances were observed for pine needle biomass burning organic aerosol (BBOA) collected with PILS and filter sampling. The water soluble fraction of BBOA is considerably smaller than for SOA, and a number of unique peaks were detectable only by the filter/acetonitrile method. The combination of PILS collection with HR-ESI-MS analysis offers a new approach for molecular analysis of the water-soluble organic fraction in biogenic SOA, aged photochemical smog, and BBOA.

  8. TWO EXTRASOLAR ASTEROIDS WITH LOW VOLATILE-ELEMENT MASS FRACTIONS

    SciTech Connect

    Jura, M.; Xu, S.; Klein, B.; Zuckerman, B.; Koester, D. E-mail: sxu@astro.ucla.edu E-mail: ben@astro.ucla.edu

    2012-05-01

    Using ultraviolet spectra obtained with the Cosmic Origins Spectrograph on the Hubble Space Telescope, we extend our previous ground-based optical determinations of the composition of the extrasolar asteroids accreted onto two white dwarfs, GD 40 and G241-6. Combining optical and ultraviolet spectra of these stars with He-dominated atmospheres, 13 and 12 polluting elements are confidently detected in GD 40 and G241-6, respectively. For the material accreted onto GD 40, the volatile elements C and S are deficient by more than a factor of 10 and N by at least a factor of 5 compared to their mass fractions in primitive CI chondrites and approach what is inferred for bulk Earth. A similar pattern is found for G241-6 except that S is undepleted. We have also newly detected or placed meaningful upper limits for the amount of Cl, Al, P, Ni, and Cu in the accreted matter. Extending results from optical studies, the mass fractions of refractory elements in the accreted parent bodies are similar to what is measured for bulk Earth and chondrites. Thermal processing, perhaps interior to a snow line, appears to be of central importance in determining the elemental compositions of these particular extrasolar asteroids.

  9. Mass dependent isotope fractionation during impacts induced the Archaean mass-independent fractionation of sulphur: Evidence against Great Oxidation Event

    NASA Astrophysics Data System (ADS)

    Huang, H.

    2010-12-01

    A prevailing hypothesis, low-oxygen level of the Archaean atmosphere, relies strongly on the presence of strong mass-independent fractionation (MIF) of the sulfur isotopes in sulfide- and sulfate-bearing minerals older than 2.4 billion years. Actually, there is “a broad overlap between MIF signals observed within Archaean sedimentary sequences and periods of enhanced asteroid impacts represented by impact ejecta/fallout units”(Glikson 2010) (Fig. 1). Moreover, usually MIF- related sulphur occurs in the Archaean sedimentary rocks as pyrite (FeS2) which has been found in the K-T boundary clay beds and in several identified impact craters, which is an independent argument in favor of pyrites could be the product of impact. Impact processes (vaporization and condensation) are sufficient to explain the MIF signals following the principle: the earlier the condensed material, the more enriched in lighter isotopes (Huang 2010). The nature of the MIF of the sulfur isotopes is that the fractionation of isotope is still mass dependent during impacts, which means the measured nonzero Δ33S values of Archean sulfide- and sulfate-bearing minerals indicate that their different condensation sequences. Another important line of evidence that support the impact-generated MIF of the sulfur isotopes comes from the various iron isotope values of the pyrites especially those with iron isotope heterogeneity at grain scale. Thus, it is clear that the signals are the markers of impact rather than O2 poor atmosphere. Furthermore, this can also account for the lack of MIF-S in several Archaean units before 2.4 billion years. Figure 1 Plot of mass-independent fractionation of sulphur and asteroid impact events with age. Modified from Glikson (2010)

  10. Mass Spectrometric Analysis of Pristine Aerosol Particles During the wet Season of Amazonia - Detection of Primary Biological Particles?

    NASA Astrophysics Data System (ADS)

    Schneider, J.; Zorn, S. R.; Freutel, F.; Borrmann, S.; Chen, Q.; Farmer, D. K.; Jimenez, J. L.; Flores, M.; Roldin, P.; Artaxo, P.; Martin, S. T.

    2008-12-01

    mass spectra that were obtained during AMAZE. First results indicate that the mass spectra of organic aerosol particle sampled during AMAZE show a size dependence, thereby indicating a size-dependent chemical composition of the aerosol particles. A detailed comparison between the laboratory data and the AMS mass spectra of the fraction of large particles sampled during AMAZE will be presented.

  11. Reduction in biomass burning aerosol light absorption upon humidification: Roles of inorganically-induced hygroscopicity, particle collapse, and photoacoustic heat and mass transfer

    SciTech Connect

    lewis, Kristen A.; Arnott, W. P.; Moosmuller, H.; Chakrabarti, Raj; Carrico, Christian M.; Kreidenweis, Sonia M.; Day, Derek E.; Malm, William C.; Laskin, Alexander; Jimenez, Jose L.; Ulbrich, Ingrid M.; Huffman, John A.; Onasch, Timothy B.; Trimborn, Achim; Liu, Li; Mishchenko, M.

    2009-11-27

    Smoke particle emissions from the combustion of biomass fuels typical for the western and southeastern United States were studied and compared under high humidity and ambient conditions in the laboratory. The fuels used are Montana ponderosa pine (Pinus ponderosa), southern California chamise (Adenostoma fasciculatum), and Florida saw palmetto (Serenoa repens). Information on the non-refractory chemical composition of biomass burning aerosol from each fuel was obtained with an aerosol mass spectrometer and through estimation of the black carbon concentration from light absorption measurements at 870 nm. Changes in the optical and physical particle properties under high humidity conditions were observed for hygroscopic smoke particles containing substantial inorganic mass fractions that were emitted from combustion of chamise and palmetto fuels. Light scattering cross sections increased under high humidity for these particles, consistent with the hygroscopic growth measured for 100 nm particles in HTDMA measurements. Photoacoustic measurements of aerosol light absorption coefficients reveal a 20% reduction with increasing relative humidity, contrary to the expectation of light absorption enhancement by the liquid coating taken up by hygroscopic particles. This reduction is hypothesized to arise from two mechanisms: 1. Shielding of inner monomers after particle consolidation or collapse with water uptake; 2. The contribution of mass transfer through evaporation and condensation at high relative humidity to the usual heat transfer pathway for energy release by laser heated particles in the photoacoustic measurement of aerosol light absorption. The mass transfer contribution is used to evaluate the fraction of aerosol surface covered with liquid water solution as a function of RH.

  12. Assessment of source apportionment by Positive Matrix Factorization analysis on fine and coarse urban aerosol size fractions

    NASA Astrophysics Data System (ADS)

    Karanasiou, A. A.; Siskos, P. A.; Eleftheriadis, K.

    This study was conducted in order to investigate the differences observed in source profiles in the urban environment, when chemical composition parameters from different aerosol size fractions are subjected to factor analysis. Source apportionment was performed in an urban area where representative types of emission sources are present. PM 10 and PM 2 samples were collected within the Athens Metropolitan area and analysed for trace elements, inorganic ions and black carbon. Analysis by two-way and three-way Positive Matrix Factorization was performed, in order to resolve sources from data obtained for the fine and coarse aerosol fractions. A difference was observed: seven factors describe the best solution in PMF3 while six factors in PMF2. Six factors derived from PMF3 analysis correspond to those described by the PMF2 solution for the fine and coarse particles separately. These sources were attributed to road dust, marine aerosol, soil, motor vehicles, biomass burning, and oil combustion. The additional source resolved by PMF3 was attributed to a different type of road dust. Combustion sources (oil combustion and biomass burning) were correctly attributed by PMF3 solely to the fine fraction and the soil source to the coarse fraction. However, a motor vehicle's contribution to the coarse fraction was found only by three-way PMF. When PMF2 was employed in PM 10 concentrations the optimum solution included six factors. Four source profiles corresponded to the previously identified as vehicles, road dust, biomass burning and marine aerosol, while two could not be clearly identified. Source apportionment by PMF2 analysis based solely on PM 10 aerosol composition data, yielded unclear results, compared to results from PMF2 and PMF3 analyses on fine and coarse aerosol composition data.

  13. Time-resolved mass concentration, composition and sources of aerosol particles in a metropolitan underground railway station

    NASA Astrophysics Data System (ADS)

    Salma, Imre; Weidinger, Tamás; Maenhaut, Willy

    Aerosol samples were collected using a stacked filter unit (SFU) for PM10-2.0 and PM2.0 size fractions on the platform of a metropolitan underground railway station in downtown Budapest. Temporal variations in the PM10 mass concentration and wind speed and direction were determined with time resolutions of 30 and 4 s using a tapered-element oscillating microbalance (TEOM) and a wind monitor, respectively. Sample analysis involved gravimetry for particulate mass, and particle-induced X-ray emission spectrometry (PIXE) for elemental composition. Diurnal variation of the PM10 mass concentration exhibited two peaks, one at approximately 07:00 h and the other at approximately 17:00 h. The mean±SD PM10 mass concentration for working hours was 155±55 μg m -3. Iron, Mn, Ni, Cu, and Cr concentrations were higher than in outdoor air by factors between 5 and 20, showing substantial enrichment compared to both the average crustal rock composition and the average outdoor aerosol composition. Iron accounted for 40% and 46% of the PM10-2.0 and PM2.0 masses, respectively, and 72% of the PM10 mass was associated with the PM10-2.0 size fraction. The aerosol composition in the metro station (in particular the abundance of the metals mentioned above) is quite different from the average outdoor downtown composition. Mechanical wear and friction of electric conducting rails and bow sliding collectors, ordinary rails and wheels, as well as resuspension, were identified as the primary sources. Possible health implications based on comparison to various limit values and to data available for other underground railways are discussed.

  14. Using Raman-lidar-based regularized microphysical retrievals and Aerosol Mass Spectrometer measurements for the characterization of biomass burning aerosols

    NASA Astrophysics Data System (ADS)

    Samaras, Stefanos; Nicolae, Doina; Böckmann, Christine; Vasilescu, Jeni; Binietoglou, Ioannis; Labzovskii, Lev; Toanca, Florica; Papayannis, Alexandros

    2015-10-01

    In this work we extract the microphysical properties of aerosols for a collection of measurement cases with low volume depolarization ratio originating from fire sources captured by the Raman lidar located at the National Institute of Optoelectronics (INOE) in Bucharest. Our algorithm was tested not only for pure smoke but also for mixed smoke and urban aerosols of variable age and growth. Applying a sensitivity analysis on initial parameter settings of our retrieval code was proved vital for producing semi-automatized retrievals with a hybrid regularization method developed at the Institute of Mathematics of Potsdam University. A direct quantitative comparison of the retrieved microphysical properties with measurements from a Compact Time of Flight Aerosol Mass Spectrometer (CToF-AMS) is used to validate our algorithm. Microphysical retrievals performed with sun photometer data are also used to explore our results. Focusing on the fine mode we observed remarkable similarities between the retrieved size distribution and the one measured by the AMS. More complicated atmospheric structures and the factor of absorption appear to depend more on particle radius being subject to variation. A good correlation was found between the aerosol effective radius and particle age, using the ratio of lidar ratios (LR: aerosol extinction to backscatter ratios) as an indicator for the latter. Finally, the dependence on relative humidity of aerosol effective radii measured on the ground and within the layers aloft show similar patterns.

  15. Chemical composition and characteristics of ambient aerosols and rainwater residues during Indian summer monsoon: Insight from aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Chakraborty, Abhishek; Gupta, Tarun; Tripathi, Sachchida N.

    2016-07-01

    Real time composition of non-refractory submicron aerosol (NR-PM1) is measured via Aerosol mass spectrometer (AMS) for the first time during Indian summer monsoon at Kanpur, a polluted urban location located at the heart of Indo Gangetic Plain (IGP). Submicron aerosols are found to be dominated by organics followed by nitrate. Source apportionment of organic aerosols (OA) via positive matrix factorization (PMF) revealed several types of secondary/oxidized and primary organic aerosols. On average, OA are completely dominated by oxidized OA with a very little contribution from biomass burning OA. During rain events, PM1 concentration is decreased almost by 60%, but its composition remains nearly the same. Oxidized OA showed slightly more decrease than primary OAs, probably due to their higher hygroscopicity. The presence of organo nitrates (ON) is also detected in ambient aerosols. Apart from real-time sampling, collected fog and rainwater samples were also analyzed via AMS in offline mode and in the ICP-OES (Inductively coupled plasma - Optical emission spectrometry) for elements. The presence of sea salt, organo nitrates and sulfates has been observed. Rainwater residues are also dominated by organics but their O/C ratios are 15-20% lower than the observed values for ambient OA. Alkali metals such as Ca, Na, K are found to be most abundant in the rainwater followed by Zn. Rainwater residues are also found to be much less oxidized than the aerosols present inside the fog water, indicating presence of less oxidized organics. These findings indicate that rain can act as an effective scavenger of different types of pollutants even for submicron particle range. Rainwater residues also contain organo sulfates which indicate that some portion of the dissolved aerosols has undergone aqueous processing, possibly inside the cloud. Highly oxidized and possibly hygroscopic OA during monsoon period compared to other seasons (winter, post monsoon), indicates that they can act

  16. Secondary Aerosol Formation in the planetary boundary layer observed by aerosol mass spectrometry on a Zeppelin NT

    NASA Astrophysics Data System (ADS)

    Rubach, Florian; Trimborn, Achim; Mentel, Thomas; Wahner, Andreas; Zeppelin Pegasos-Team 2012

    2014-05-01

    The airship Zeppelin NT is an airborne platform capable of flying at low speed throughout the entire planetary boundary layer (PBL). In combination with the high scientific payload of more than 1 ton, the Zeppelin is an ideal platform to study regional processes in the lowest layers of the atmosphere with high spatial resolution. Atmospheric aerosol as a medium long lived tracer substance is of particular interest due to its influence on the global radiation budget. Due its lifetime of up to several days secondaray aerosol at a certain location can result from local production or from transport processes. For aerosol measurements on a Zeppelin, a High-Resolution Time-of-Flight Aerosol Mass spectrometer (DeCarlo et al, 2006) was adapted to the requirements posed by an airborne platform. A weight reduction of over 20 % compared to the commercial instrument was achieved, while space occupation and footprint were each reduced by over 25 %. Within the PEGASOS project, the instrument was part of 10 measurement flight days over the course of seven weeks. Three flights were starting from Rotterdam, NL, seven flights were starting from Ozzano in the Po Valley, IT. Flight patterns included vertical profiles to study the dynamics of the PBL and cross sections through regions of interest to shed light on local production and transport processes. Analysis of data from transects between the Apennin and San Pietro Capofiume in terms of "residence time of air masses in the Po valley" indicates that aerosol nitrate has only local sources while aerosol sulfate is dominated by transport. The organic aerosol component has significant contributions of both processes. The local prodcution yields are commensurable with imultaneously observed precursor concentrations and oxidant levels. The PEGASOS project is funded by the European Commission under the Framework Programme 7 (FP7-ENV-2010-265148). DeCarlo, P.F. et al (2006), Anal. Chem., 78, 8281-8289.

  17. Sources and composition of submicron organic mass in marine aerosol particles

    NASA Astrophysics Data System (ADS)

    Frossard, Amanda A.; Russell, Lynn M.; Burrows, Susannah M.; Elliott, Scott M.; Bates, Timothy S.; Quinn, Patricia K.

    2014-11-01

    The sources and composition of atmospheric marine aerosol particles (aMA) have been investigated with a range of physical and chemical measurements from open-ocean research cruises. This study uses the characteristic functional group composition (from Fourier transform infrared spectroscopy) of aMA from five ocean regions to show the following: (i) The organic functional group composition of aMA that can be identified as mainly atmospheric primary marine (ocean derived) aerosol particles (aPMA) is 65 ± 12% hydroxyl, 21 ± 9% alkane, 6 ± 6% amine, and 7 ± 8% carboxylic acid functional groups. Contributions from photochemical reactions add carboxylic acid groups (15%-25%), shipping effluent in seawater and ship emissions add additional alkane groups (up to 70%), and coastal or continental emissions mix in alkane and carboxylic acid groups. (ii) The organic composition of aPMA is nearly identical to model-generated primary marine aerosol particles from bubbled seawater (gPMA, which has 55 ± 14% hydroxyl, 32 ± 14% alkane, and 13 ± 3% amine functional groups), indicating that its overall functional group composition is the direct consequence of the organic constituents of the seawater source. (iii) While the seawater organic functional group composition was nearly invariant across all three ocean regions studied and the ratio of organic carbon to sodium (OC/Na+) in the gPMA remained nearly constant over a broad range of chlorophyll a concentrations, the gPMA alkane group fraction appeared to increase with chlorophyll a concentrations (r = 0.66). gPMA from productive seawater had a larger fraction of alkane functional groups (42 ± 9%) compared to gPMA from nonproductive seawater (22 ± 10%), perhaps due to the presence of surfactants in productive seawater that stabilize the bubble film and lead to preferential drainage of the more soluble (lower alkane group fraction) organic components. gPMA has a hydroxyl group absorption peak location characteristic of

  18. Real-time analysis of ambient organic aerosols using aerosol flowing atmospheric-pressure afterglow mass spectrometry (AeroFAPA-MS)

    NASA Astrophysics Data System (ADS)

    Brüggemann, Martin; Karu, Einar; Stelzer, Torsten; Hoffmann, Thorsten

    2015-04-01

    Organic aerosol accounts for a major fraction of atmospheric aerosols and has implications on the earth's climate and human health. However, due to the chemical complexity its measurement remains a major challenge for analytical instrumentation.1 Here, we present the development, characterization and application of a new soft ionization technique that allows mass spectrometric real-time detection of organic compounds in ambient aerosols. The aerosol flowing atmospheric-pressure afterglow (AeroFAPA) ion source utilizes a helium glow discharge plasma to produce excited helium species and primary reagent ions. Ionization of the analytes occurs in the afterglow region after thermal desorption and results mainly in intact molecular ions, facilitating the interpretation of the acquired mass spectra. In the past, similar approaches were used to detect pesticides, explosives or illicit drugs on a variety of surfaces.2,3 In contrast, the AeroFAPA source operates 'online' and allows the detection of organic compounds in aerosols without a prior precipitation or sampling step. To our knowledge, this is the first application of an atmospheric-pressure glow discharge ionization technique to ambient aerosol samples. We illustrate that changes in aerosol composition and concentration are detected on the time scale of seconds and in the ng-m-3 range. Additionally, the successful application of AeroFAPA-MS during a field study in a mixed forest region in Central Europe is presented. Several oxidation products of monoterpenes were clearly identified using the possibility to perform tandem MS experiments. The acquired data are in agreement with previous studies and demonstrate that AeroFAPA-MS is a suitable tool for organic aerosol analysis. Furthermore, these results reveal the potential of this technique to enable new insights into aerosol formation, growth and transformation in the atmosphere. References: 1) IPCC, 2013: Summary for Policymakers. In: Climate Change 2013: The

  19. Fractal morphology, imaging and mass spectrometry of single aerosol particles in flight (CXIDB ID 16)

    DOE Data Explorer

    Loh, N. Duane

    2012-06-20

    This deposition includes the aerosol diffraction images used for phasing, fractal morphology, and time-of-flight mass spectrometry. Files in this deposition are ordered in subdirectories that reflect the specifics.

  20. Unraveling the Complexity of Atmospheric Aerosol: Insights from Ultrahigh Resolution Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Mazzoleni, Lynn R.; Zhao, Yunzhu; Samburova, Vera; Gannet Hallar, A.; Lowenthal, Douglas

    2016-04-01

    Atmospheric aerosol organic matter (AOM) is a complex mixture of thousands of organic compounds, which may have significant influence on the climate-relevant properties of atmospheric aerosols. An improved understanding of the molecular composition of AOM is needed to evaluate the effect of aerosol composition upon aerosol physical properties. Products of gas, aqueous and particle phase reactions contribute to the aerosol organic mass. Thus, ambient aerosols carry a complex array of AOM components with variable chemical signatures depending upon its origin and aerosol life-cycle processes. In this work, ultrahigh-resolution Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) was used to characterize ambient aerosol AOM collected at the Storm Peak Laboratory (3210 m a.s.l.) near Steamboat Springs, CO. Thousands of molecular formulas were assigned in the mass range of m/z 100-800 after negative-ion electrospray ionization. Using multivariate statistical analysis, correlations between the site meteorological conditions and specific molecular compositions were identified. For example, days with strong UV radiation and high temperature were found to contain large numbers of biogenic SOA molecular formulas. Similarly, days with high relative humidity and high sulfate concentrations were found to contain many sulfur-containing compounds, suggesting their aqueous phase formation.

  1. Evaluation of Aerosol Mixing State Classes in the GISS Modele-matrix Climate Model Using Single-particle Mass Spectrometry Measurements

    NASA Technical Reports Server (NTRS)

    Bauer, Susanne E.; Ault, Andrew; Prather, Kimberly A.

    2013-01-01

    Aerosol particles in the atmosphere are composed of multiple chemical species. The aerosol mixing state, which describes how chemical species are mixed at the single-particle level, provides critical information on microphysical characteristics that determine the interaction of aerosols with the climate system. The evaluation of mixing state has become the next challenge. This study uses aerosol time-of-flight mass spectrometry (ATOFMS) data and compares the results to those of the Goddard Institute for Space Studies modelE-MATRIX (Multiconfiguration Aerosol TRacker of mIXing state) model, a global climate model that includes a detailed aerosol microphysical scheme. We use data from field campaigns that examine a variety of air mass regimens (urban, rural, and maritime). At all locations, polluted areas in California (Riverside, La Jolla, and Long Beach), a remote location in the Sierra Nevada Mountains (Sugar Pine) and observations from Jeju (South Korea), the majority of aerosol species are internally mixed. Coarse aerosol particles, those above 1 micron, are typically aged, such as coated dust or reacted sea-salt particles. Particles below 1 micron contain large fractions of organic material, internally-mixed with sulfate and black carbon, and few external mixtures. We conclude that observations taken over multiple weeks characterize typical air mass types at a given location well; however, due to the instrumentation, we could not evaluate mass budgets. These results represent the first detailed comparison of single-particle mixing states in a global climate model with real-time single-particle mass spectrometry data, an important step in improving the representation of mixing state in global climate models.

  2. Evaluation of aerosol mixing state classes in the GISS modelE-MATRIX climate model using single-particle mass spectrometry measurements

    NASA Astrophysics Data System (ADS)

    Bauer, Susanne E.; Ault, Andrew; Prather, Kimberly A.

    2013-09-01

    Aerosol particles in the atmosphere are composed of multiple chemical species. The aerosol mixing state, which describes how chemical species are mixed at the single-particle level, provides critical information on microphysical characteristics that determine the interaction of aerosols with the climate system. The evaluation of mixing state has become the next challenge. This study uses aerosol time-of-flight mass spectrometry (ATOFMS) data and compares the results to those of the Goddard Institute for Space Studies modelE-MATRIX (Multiconfiguration Aerosol TRacker of mIXing state) model, a global climate model that includes a detailed aerosol microphysical scheme. We use data from field campaigns that examine a variety of air mass regimens (urban, rural, and maritime). At all locations, polluted areas in California (Riverside, La Jolla, and Long Beach), a remote location in the Sierra Nevada Mountains (Sugar Pine) and observations from Jeju (South Korea), the majority of aerosol species are internally mixed. Coarse aerosol particles, those above 1 µm, are typically aged, such as coated dust or reacted sea-salt particles. Particles below 1 µm contain large fractions of organic material, internally mixed with sulfate and black carbon, and few external mixtures. We conclude that observations taken over multiple weeks characterize typical air mass types at a given location well; however, due to the instrumentation, we could not evaluate mass budgets. These results represent the first detailed comparison of single-particle mixing states in a global climate model with real-time single-particle mass spectrometry data, an important step in improving the representation of mixing state in global climate models.

  3. The organic fraction of bubble-generated, accumulation mode Sea Spray Aerosol (SSA)

    NASA Astrophysics Data System (ADS)

    Modini, R. L.; Harris, B.; Ristovski, Z. D.

    2010-03-01

    Recent studies have detected a dominant accumulation mode (~100 nm) in the Sea Spray Aerosol (SSA) number distribution. There is evidence to suggest that particles in this mode are composed primarily of organics. To investigate this hypothesis we conducted experiments on NaCl, artificial SSA and natural SSA particles with a Volatility-Hygroscopicity-Tandem-Differential-Mobility-Analyser (VH-TDMA). NaCl particles were atomiser generated and a bubble generator was constructed to produce artificial and natural SSA particles. Natural seawater samples for use in the bubble generator were collected from biologically active, terrestrially-affected coastal water in Moreton Bay, Australia. Differences in the VH-TDMA-measured volatility curves of artificial and natural SSA particles were used to investigate and quantify the organic fraction of natural SSA particles. Hygroscopic Growth Factor (HGF) data, also obtained by the VH-TDMA, were used to confirm the conclusions drawn from the volatility data. Both datasets indicated that the organic fraction of our natural SSA particles evaporated in the VH-TDMA over the temperature range 170-200 °C. The organic volume fraction for 71-77 nm natural SSA particles was 8±6%. Organic volume fraction did not vary significantly with varying water residence time (40 s to 24 h) in the bubble generator or SSA particle diameter in the range 38-173 nm. At room temperature we measured shape- and Kelvin-corrected HGF at 90% RH of 2.46±0.02 for NaCl, 2.35±0.02 for artifical SSA and 2.26±0.02 for natural SSA particles. Overall, these results suggest that the natural accumulation mode SSA particles produced in these experiments contained only a minor organic fraction, which had little effect on hygroscopic growth. Our measurement of 8±6% is an order of magnitude below two previous measurements of the organic fraction in SSA particles of comparable sizes. We stress that our results were obtained using coastal seawater and they can't necessarily

  4. The organic fraction of bubble-generated, accumulation mode Sea Spray Aerosol (SSA)

    NASA Astrophysics Data System (ADS)

    Modini, R. L.; Harris, B.; Ristovski, Z. D.

    2009-10-01

    Recent studies have detected a dominant accumulation mode (~100 nm) in the Sea Spray Aerosol (SSA) number distribution. There is evidence to suggest that particles in this mode are composed primarily of organics. To investigate this hypothesis we conducted experiments on NaCl, artificial SSA and natural SSA particles with a Volatility-Hygroscopicity-Tandem-Differential-Mobility-Analyser (VH-TDMA). NaCl particles were atomiser generated and a bubble generator was constructed to produce artificial and natural SSA particles. Natural seawater samples for use in the bubble generator were collected from biologically active, terrestrially-affected coastal water in Moreton Bay, Australia. Differences in the VH-TDMA-measured volatility curves of artificial and natural SSA particles were used to investigate and quantify the organic fraction of natural SSA particles. Hygroscopic Growth Factor (HGF) data, also obtained by the VH-TDMA, were used to confirm the conclusions drawn from the volatility data. Both datasets indicated that the organic fraction of our natural SSA particles evaporated in the VH-TDMA over the temperature range 170-200°C. The organic volume fraction for 71-77 nm natural SSA particles was 8±6%. Organic volume fraction did not vary significantly with varying water residence time (40 s0 to 24 h) in the bubble generator or SSA particle diameter in the range 38-173 nm. At room temperature we measured shape- and Kelvin-corrected HGF at 90% RH of 2.46±0.02 for NaCl, 2.35±0.02 for artifical SSA and 2.26±0.02 for natural SSA particles. Overall, these results suggest that the natural accumulation mode SSA particles produced in these experiments contained only a minor organic fraction, which had little effect on hygroscopic growth. Our measurement of 8±6% is an order of magnitude below two previous measurements of the organic fraction in SSA particles of comparable sizes. Further studies with a variety of different seawaters are required to better quantify how

  5. New mass measurement method of aerosol particle using vibrating probe particle controlled by radiation pressure

    NASA Astrophysics Data System (ADS)

    Hariyama, Tatsuo; Takaya, Yasuhiro; Miyoshi, Takashi

    2005-11-01

    Aerosol particles with sub-micro meter size inhaled into respiratory systems cause serious damage to human body. In order to evaluate the health effects of the particles, classification methods of the particles with size and mass are needed. Several measurement methods of the particle size are established. However, conventional mass measurement methods are not enough to measure the particles with sub- pico gram. We propose a new mass measurement method of the aerosol particles based on laser trapping. In this method, an optically trapped silica particle is used as a measuring probe particle. The probe particle is trapped at a beam waist of the focused laser light and is forced to vibrate by deflecting the beam waist using AOD. The vibrating probe particle has a resonance frequency because it is governed by the spring-mass-damper system. When an aerosol particle is attached to the probe particle, the resonance frequency shifts according to the increase of the total mass. The mass of the aerosol particle can be measured from the shift of the resonance frequency. Experimentally, it is confirmed that the probe particle is governed by the spring-mass-damper system and has a resonance frequency. When a silica fine particle of 3pg in mass used as an aerosol particle is attached to the probe particle, the resonance frequency shift occurs as expected in the dynamic system and the fine particle mass can be measured based on the proposed method.

  6. Variability of Marine Aerosol Fine-Mode Fraction and Estimates of Anthropogenic Aerosol Component Over Cloud-Free Oceans from the Moderate Resolution Imaging Spectroradiometer (MODIS)

    NASA Technical Reports Server (NTRS)

    Yu, Hongbin; Chin, Mian; Remer, Lorraine A.; Kleidman, Richard G.; Bellouin, Nicolas; Bian, Huisheng; Diehl, Thomas

    2009-01-01

    In this study, we examine seasonal and geographical variability of marine aerosol fine-mode fraction (f(sub m)) and its impacts on deriving the anthropogenic component of aerosol optical depth (tau(sub a)) and direct radiative forcing from multispectral satellite measurements. A proxy of f(sub m), empirically derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 5 data, shows large seasonal and geographical variations that are consistent with the Goddard Chemistry Aerosol Radiation Transport (GOCART) and Global Modeling Initiative (GMI) model simulations. The so-derived seasonally and spatially varying f(sub m) is then implemented into a method of estimating tau(sub a) and direct radiative forcing from the MODIS measurements. It is found that the use of a constant value for fm as in previous studies would have overestimated Ta by about 20% over global ocean, with the overestimation up to 45% in some regions and seasons. The 7-year (2001-2007) global ocean average tau(sub a) is 0.035, with yearly average ranging from 0.031 to 0.039. Future improvement in measurements is needed to better separate anthropogenic aerosol from natural ones and to narrow down the wide range of aerosol direct radiative forcing.

  7. Determination of particulate lead during MILAGRO/MCMA-2006 using Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Salcedo, D.; Onasch, T. B.; Aiken, A. C.; Williams, L. R.; de Foy, B.; Cubison, M. J.; Worsnop, D. R.; Molina, L. T.; Jimenez, J. L.

    2010-02-01

    We report the first measurements of particulate lead (Pb) from Aerodyne Aerosol Mass Spectrometers, which were deployed in and around Mexico City during the Megacity Initiative: Local and Global Research Observations (MILAGRO)/Mexico City Metropolitan Area 2006 (MCMA-2006) field campaigns. The high resolution mass spectrometer of one of the AMS instruments (HR-AMS) and the measured isotopic ratios unequivocally prove the detection of Pb in ambient particles. A substantial fraction of the lead evaporated slowly from the vaporizer of the instruments, which is indicative of species with low volatility at 600 °C. A model was developed in order to estimate the ambient particulate Pb entering the AMS from the signals in the "open" and the "closed" (or "background") mass spectrum modes of the AMS. The model suggests the presence of at least two lead fractions with ~25% of the Pb signal exhibiting rapid evaporation (1/e decay constant, τ<0.1 s) and ~75% exhibiting slow evaporation (τ~2.4 min) at the T0 urban supersite and a different fraction (70% prompt and 30% slow evaporation) at a site northwest from the metropolitan area (PEMEX site). From laboratory experiments with pure Pb(NO3)2 particles, we estimated that the Pb ionization efficiency relative to nitrate (RIEPb) is 0.5. Comparison of time series of AMS Pb with other measurements carried out at T0 (using Proton Induced X-ray Emission (PIXE), Inductively-Coupled Plasma Mass Spectrometry (ICP-MS) and single-particle counts from an Aerosol Time-of-Fight Mass Spectrometer (ATOFMS)) shows similar levels (for PIXE and ICP-MS) and substantial correlation. During part of the campaign, sampling at T0 was alternated every 10 min with an Aerosol Concentrator, which enabled the detection of signals for PbCl+ and PbS+ ions. PbS+ displays the signature of a slowly evaporating species, while PbCl+ appears to arise only from fast evaporation, which is likely due to the higher vapor pressure of the compounds generating Pb

  8. Determination of particulate lead using aerosol mass spectrometry: MILAGRO/MCMA-2006 observations

    NASA Astrophysics Data System (ADS)

    Salcedo, D.; Onasch, T. B.; Aiken, A. C.; Williams, L. R.; de Foy, B.; Cubison, M. J.; Worsnop, D. R.; Molina, L. T.; Jimenez, J. L.

    2010-06-01

    We report the first measurements of particulate lead (Pb) from Aerodyne Aerosol Mass Spectrometers, which were deployed in and around Mexico City during the Megacity Initiative: Local and Global Research Observations (MILAGRO)/Mexico City Metropolitan Area 2006 (MCMA-2006) field campaigns. The high resolution mass spectrometer of one of the AMS instruments (HR-AMS) and the measured isotopic ratios unequivocally prove the detection of Pb in ambient particles. A substantial fraction of the lead evaporated slowly from the vaporizer of the instruments, which is indicative of species with low volatility at 600 °C. A model was developed in order to estimate the ambient particulate Pb entering the AMS from the signals in the "open" and the "closed" (or "background") mass spectrum modes of the AMS. The model suggests the presence of at least two lead fractions with ~25% of the Pb signal exhibiting rapid evaporation (1/e decay constant, τ<0.1 s) and ~75% exhibiting slow evaporation (τ~2.4 min) at the T0 urban supersite and a different fraction (70% prompt and 30% slow evaporation) at a site northwest from the metropolitan area (PEMEX site). From laboratory experiments with pure Pb(NO3)2 particles, we estimated that the Pb ionization efficiency relative to nitrate (RIEPb) is 0.5. Comparison of time series of AMS Pb with other measurements carried out at the T0 supersite during MILAGRO (using Proton Induced X-ray Emission (PIXE), Inductively-Coupled Plasma Mass Spectrometry (ICP-MS) and single-particle counts from an Aerosol Time-of-Fight Mass Spectrometer (ATOFMS)) shows similar levels (for PIXE and ICP-MS) and substantial correlation. During part of the campaign, sampling at T0 was alternated every 10 min with an Aerosol Concentrator, which enabled the detection of signals for PbCl+ and PbS+ ions. PbS+ displays the signature of a slowly evaporating species, while PbCl+ appears to arise only from fast evaporation, which is likely due to the higher vapor pressure of the

  9. Determination of particulate lead during MILAGRO / MCMA-2006 using Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Salcedo, Dara; Onasch, T. B.; Aiken, A. C.; Williams, L. R.; de Foy, B.; Cubison, M. J.; Worsnop, D. R.; Molina, L. T.; Jimenez, J. L.

    2010-05-01

    We report the first measurements of particulate lead (Pb) from Aerodyne Aerosol Mass Spectrometers, which were deployed in and around Mexico City during the Megacity Initiative: Local and Global Research Observations (MILAGRO) / Mexico City Metropolitan Area 2006 (MCMA-2006) field campaigns. The high resolution mass spectrometer of one of the AMS instruments (HR-AMS) and the measured isotopic ratios unequivocally prove the detection of Pb in ambient particles. A substantial fraction of the lead evaporated slowly from the vaporizer of the instruments, which is indicative of species with low volatility at 600oC. A model was developed in order to estimate the ambient particulate Pb entering the AMS from the signals in the "open" and the "closed" (or "background") mass spectrum modes of the AMS. The model suggests the presence of at least two lead fractions with ~25% of the Pb signal exhibiting rapid evaporation (1/e decay constant, τ < 0.1 s) and ~75% exhibiting slow evaporation (τ ~2.4 min) at T0 and a different fraction (70% prompt and 30% slow evaporation) at a site northwest from the metropolitan area (PEMEX32 site). From laboratory experiments with pure Pb(NO3)2 particles, we estimated that the Pb ionization efficiency relative to nitrate (RIEPb) is 0.5. Comparison of time series of AMS Pb with other measurements carried out at the T0 urban supersite during MILAGRO (using Proton Induced X-ray Emission (PIXE), Inductively-Coupled Plasma Mass Spectrometry (ICP-MS) and single-particle counts from an Aerosol Time-of-Fight Mass Spectrometer (ATOFMS)) shows similar levels (for PIXE and ICP-MS) and substantial correlation. During part of the campaign, sampling at T0 was alternated every 10 minutes with an Aerosol Concentrator, which enabled the detection of signals for PbCl+ and PbS+ ions. PbS+ displays the signature of a slowly evaporating species, while PbCl+ appears to arise only from fast evaporation, which is likely due to the higher vapor pressure of the

  10. Studies of aerosol at a coastal site using two aerosol mass spectrometry instruments and identification of biogenic particle types

    NASA Astrophysics Data System (ADS)

    Dall'Osto, M.; Harrison, R. M.; Furutani, H.; Prather, K. A.; Coe, H.; Allan, J. D.

    2005-10-01

    During August 2004 an Aerosol Time-of-Flight Mass Spectrometer (TSI ATOFMS Model 3800-100) and an Aerodyne Aerosol Mass Spectrometer (AMS) were deployed at Mace Head during the NAMBLEX campaign. Single particle data (size, positive and negative mass spectra) from the ATOFMS were imported into ART 2a, a neural network algorithm, which assigns individual particles to clusters on the basis of their mass spectral similarities. Results are very consistent with previous time consuming manual classifications (Dall'Osto et al., 2004). Three broad classes were found: sea-salt, dust and carbon-containing particles, with a number of sub-classes within each. The Aerodyne (AMS) instrument was also used during NAMBLEX, providing online, real time measurements of the mass of non-refractory components of aerosol particles as function of their size. The ATOFMS detected a type of particle not identified in our earlier analysis, with a strong signal at m/z 24, likely due to magnesium. This type of particle was detected during the same periods as pure unreacted sea salt particles and is thought to be biogenic, originating from the sea surface. AMS data are consistent with this interpretation, showing an additional organic peak in the corresponding size range at times when the Mg-rich particles are detected. The work shows the ATOFMS and AMS to be largely complementary, and to provide a powerful instrumental combination in studies of atmospheric chemistry.

  11. Sulfur Mass-Independent Fractionation in Atmospheric Formation of Volcanic Sulfate

    NASA Astrophysics Data System (ADS)

    Lanciki, A.; Cole-Dai, J.; Thiemens, M. H.; Savarino, J. P.

    2009-12-01

    Volcanic eruptions emit sulfur dioxide which oxidizes to sulfuric acid aerosols in the atmosphere. Sulfate aerosols affect global climate by altering the atmospheric radiative properties. Sulfate aerosols from stratospheric eruptions can impact global climate, through their widespread distribution and relatively long atmospheric residence times (months to years). Ice cores volcanic sulfate records are often used to assess the volcanic contribution to climate change. However, sulfate signals of tropospheric eruptions in the ice core records make it difficult to evaluate the climatic impact of stratospheric eruptions in a glaciological record. But, the isotope composition of the volcanic sulfate can be used to distinguish between sulfate from stratospheric eruptions and that of tropospheric eruptions. Mass-independent fractionation (MIF) of sulfur isotopes in sulfate aerosols arises from the high-energy UV photo-oxidation of SO2, and this can be used to determine if a volcanic eruption is stratospheric, since high-energy UV is available only in the stratosphere. The stable isotopes of sulfur are compared to a standard (Canyon Diablo Triolite, FeS) in equation 1. The small delta (δ) represents the ratio of the isotope of interest to the most abundant isotope.

    δxS (‰) = [(xS/32S)sample/ [(xS/32S)std - 1] × 1000 (1)33S, calculated with the equation below. Any significant, non-zero Δ33S values indicate that the sulfate is formed via the UV-catalyzed oxidation of SO2 in the stratosphere.
    Δ33S = δ33S - 1000 × [(1 + δ34S/1000)0.515 - 1] (2)33S MIF values and have been deemed stratospheric events by this study. The 1259 AD eruption has the largest Δ33S values ever reported, beginning at +1.63 ‰ and ending with -1.49 ‰. Tambora, which has been estimated to be 2-3 times smaller in magnitude than the 1259 event, had measured Δ33S values of +0.25 ‰ to -0.28 ‰ along the timeframe of the eruption. Two of the measured events did not exhibit any

  12. Reporting and measurement of mass-dependent and mass-independent fractionation of mercury isotopes

    NASA Astrophysics Data System (ADS)

    Bergquist, B. A.; Blum, J. D.

    2007-12-01

    Hg isotope analysis by MC-ICP-MS is an important new approach for fingerprinting Hg sources and monitoring Hg redox reactions and bioaccumulation, especially with the recent discovery of mass independent Hg isotope fractionation. Unfortunately research groups have adopted different standards, definitions of delta values, and methods of isotopic measurement. We suggest that a single standard, NIST SRM 3133, be adopted for reporting the isotopic variability of Hg isotopes. Isotope ratios should be determined by sample-standard bracketing (SSB) during analysis and reported as permil (‰) deviation from SRM 3133. For the highest precision and accuracy, a Tl internal standard along with SSB should be used to correct instrumental mass bias. Measurement routines should also include on-peak zero corrections and matching of concentration and matrix between the samples and bracketing standard. For samples that display mass-dependent fractionation (MDF), only one delta value needs to be reported (δ202/198Hg). Mass-independent fractionation (MIF) (Jackson et al., 2006; Bergquist et al., 2006; Bergquist and Blum, submitted) requires additional nomenclature, and we suggest reporting MIF as the deviation in isotope ratios from the theoretical mass dependent kinetic isotope fractionation (Δxxx/198Hg)¬. External reproducibility should be monitored by analysis of secondary standards. For studies of MDF, we use an in-house secondary standard solution made from metallic Hg mined from Almaden Spain and obtain a δ202Hg of -0.55 ±0.06‰ (2SD). For studies of MIF, we use NRCC CRM DORM-2 (dogfish muscle) and obtain a mean value of δ202Hg of +0.19 ±0.13‰ (2SD), Δ201Hg of +0.89 ±0.07‰ (2SD) , and Δ199Hg of +1.07 ±0.08‰ (2SD).

  13. The water-soluble fraction of carbon, sulfur, and crustal elements in Asian aerosols and Asian soils

    NASA Astrophysics Data System (ADS)

    Duvall, R. M.; Majestic, B. J.; Shafer, M. M.; Chuang, P. Y.; Simoneit, B. R. T.; Schauer, J. J.

    We quantified the water-soluble species in 24 h average TSP (Dunhuang and Gosan) and PM1.0 (Gosan only) samples associated with the Spring 2001 Asian Dust season. Samples were analyzed for water-soluble organic carbon, water-soluble sulfur, and water-soluble crustal elements, as well as their bulk chemical composition. Water-soluble organic carbon in Gosan accounted for 28-83% (average=63%) of the particle-phase TSP total organic carbon, and 1-69% (average=23%) of the particle-phase PM1.0 organic carbon. Water-soluble sulfur, primarily in the form of sulfate, accounted for 2-22% of the TSP mass in Gosan, and 0.9-11% of the TSP mass in Dunhuang. The absolute concentrations and the soluble fraction of crustal elements in TSP samples collected at Gosan were found to correlate with the air mass source region as determined by back-trajectory analysis. For example, elevated levels of water-soluble sodium, potassium, and calcium were observed during dust events. These observations are likely the result of differences in anthropogenic sources, mineralogical composition of resuspended crustal materials, and atmospheric processing of the aerosols. Experiments were conducted using Asian soil samples to study the impact of acidification by nitric acid vapor on the solubility of crustal elements present in Asian desert and non-desert dusts. These experiments demonstrated that gaseous nitric acid attack leads to significant increases (>100% increase) in water-soluble calcium, magnesium, aluminum, manganese, and iron, while little or no increases in water-soluble sodium and potassium were observed in the soils.

  14. Mass Independent Isotopic Compositions of Aerosol Sulfate and Nitrates

    NASA Astrophysics Data System (ADS)

    Thiemens, M. H.

    2001-12-01

    For nearly a half-century stable isotope ratio measurements have been utilized as a tool to understand sources, fates, and transformation mechanisms of atmospheric molecules. Carbon and oxygen (δ 13C and δ 18O) measurements of CO2 have been instrumental in providing specific details of the carbon cycle. Without these measurements, understanding of the carbon cycle and transfer rates between reservoirs would be considerably diminished. Deuterium and oxygen isotopic measurements of atmospheric water has similarly enhanced the ability to model the atmospheric and geochemical recycling of the hydrologic cycle. Other molecules investigated include, for example, CO, CH4, N2O, SO4, NH, and Cl. The ability to interpret these high precision isotope ratio measurements relies upon a fundamental understanding of the basic physical-chemical processes which produce the alteration of the stable isotope ratio. Such processes typically include thermodynamics (viz a viz isotope exchange), kinetics, and evaporation-condensation. Though the mechanism by which these alterations occur, they all depend in some fashion upon mass differences in the isotopically substituted atoms. In 1983, Thiemens and Heidenreich (1) demonstrated that a chemical process is capable of producing an alteration of stable isotopes which was independent of mass. Subsequent to that time, it has been shown that measurements of mass independent isotopic compositions provide a new view of atmospheric process which may not be derived from single isotope ratio measurements (reviews by (2), (3)). In the past few years, mass independent isotopic compositions have been utilized to understand ancient atmospheres on both Earth and Mars (review by (4)). It has been known for decades that atmospheric sulfate is an extraordinary species. It participates in climate change in its capacity as a cloud condensation nuclei and it is a human and environmental health hazard. By the same token, aerosol nitrate is an environmental

  15. Anthropogenic sources of aerosol particles in a football stadium: Real-time characterization of emissions from cigarette smoking, cooking, hand flares, and color smoke bombs by high-resolution aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Faber, Peter; Drewnick, Frank; Veres, Patrick R.; Williams, Jonathan; Borrmann, Stephan

    2013-10-01

    Aerosol particles from several anthropogenic sources associated with football stadia including cooking, cigarette smoking, burning of color smoke bombs and hand flares were analyzed by high-resolution aerosol mass spectrometry. The physical and chemical characteristics of these different aerosols, in particular the organic fraction, were explored in laboratory studies to obtain robust references. These data were compared with field campaign results from a Bundesliga (German football league) match in the Coface Arena (Mainz, Germany) on 20th April 2012. The field measurement revealed a strongly elevated mass concentration of organic aerosols (OA) compared to background levels showing a temporal structure clearly related to the match. PMF analysis established that during the football match event cigarette smoke was the predominant component of submicron organic aerosol (67% of total OA). Cooking emissions from food outlets within the stadium correlated well with the sales figures of the catering stations and were also found to be of relevance (24% of total OA) especially in the period before kickoff. Pyrotechnics were not observed during this football match and no signatures of these sources were found in the mass spectra from the stadium measurements. All species that were elevated during the football match returned to their initial background levels within one hour after the match had finished. This demonstrates a good ventilation capacity of the open-topped Coface Arena.

  16. Effect of Vaporizer Temperature on Ambient Non-Refractory Submicron Aerosol Composition and Mass Spectra Measured by the Aerosol Mass Spectrometer

    EPA Science Inventory

    Aerodyne Aerosol Mass Spectrometers (AMS) are routinely operated with a constant vaporizer temperature (Tvap) of 600oC in order to facilitate quantitative detection of non-refractory submicron (NR-PM1) species. By analogy with other thermal desorption instrument...

  17. Mass spectrometric approaches for chemical characterisation of atmospheric aerosols: critical review of the most recent advances

    SciTech Connect

    Laskin, Alexander; Laskin, Julia; Nizkorodov, Sergey A.

    2012-06-29

    This manuscript presents an overview of the most recent instrument developments for the field and laboratory applications of mass spectrometry (MS) to investigate the chemistry and physics of atmospheric aerosols. A range of MS instruments, employing different sample introduction methods, ionisation and mass detection techniques are used both for ‘online’ and ‘offline’ characterisation of aerosols. Online MS techniques enable detection of individual particles with simultaneous measurement of particle size distributions and aerodynamic characteristics and are ideally suited for field studies that require high temporal resolution. Offline MS techniques provide a means for detailed molecular-level analysis of aerosol samples, which is essential to gain fundamental knowledge regarding aerosol chemistry, mechanisms of particle formation and atmospheric aging. Combined, complementary MS techniques provide comprehensive information on the chemical composition, size, morphology and phase of aerosols – data of key importance for evaluating hygroscopic and optical properties of particles, their health effects, understanding their origins and atmospheric evolution. Over the last few years, developments and applications of MS techniques in aerosol research have expanded remarkably as evident by skyrocketing publication statistics. Finally, the goal of this review is to present the most recent developments in the field of aerosol mass spectrometry for the time period of late 2010 to early 2012, which have not been conveyed in previous reviews.

  18. Determination of aromatic tracer compounds for environmental tobacco smoke aerosol by two step laser mass spectrometry

    NASA Astrophysics Data System (ADS)

    Morrical, Brad D.; Zenobi, Renato

    Cigarette smoking is a major cause of indoor aerosol pollution. Determination of exposure to environmental tobacco smoke (ETS) aerosol is critical to understanding health effects. Sizing studies have shown that ETS has a size distribution that is efficiently deposited into the lungs and can therefore provide effective delivery of carcinogenic compounds into the human body. Two-step laser mass spectrometry is used to analyze aromatic compounds on aerosols collected from a smoking lobby. The determination and suitability of ETS tracers on aerosols is examined. Additionally, the transport of aerosol from the smoking lobby is examined to determine what effect deposition and dilution have on the mass spectrum observed. Results from the analysis of ETS, both from lobby samples and direct cigarette sampling, show that several unique peaks are present in the mass spectrum when compared to other combustion sources, such as automobiles and diesel trucks. In particular, ions at m/ z 118, 132, 146, and 160 are consistently present and are not found in other combustion sources. For the indoor environment, where chemical transformation is much less rapid than in the outdoor environment, these ions were found to be present as soon as the first smokers appeared and persisted over the course of the day. Aerosol samples taken in the morning prior to the presence of smokers in the lobby reveal the presence of skeletal PAHs, indicative of outdoor urban traffic aerosol penetration into the building.

  19. Mechanisms of Mass-independent Fractionation of Sulfur Isotopes

    NASA Astrophysics Data System (ADS)

    Lyons, J. R.

    2006-05-01

    Sulfur mass-independent fractionation (MIF) is believed to arise from gas-phase atmospheric reactions involving SO2 and H2S [1]. However, a quantitative understanding of the mechanisms remains elusive. Here I will discuss two MIF mechanisms for sulfur isotopes, and use existing laboratory data to place constraints on these mechanisms. The relevant laboratory data includes the following: 1) Photolysis of H2S [2]; 2) spark discharge of SO2 [3]; 3) SO2 photolysis from 190-210 nm [3]; 4) SO2 photolysis at wavelengths > 220 nm [4]. Experiments 1 and 2 yielded elemental sulfur (Sel) that exhibited primarily mass-dependent fractionation, while experiment 3 produced Sel with a large MIF signature, and experiment 4 yielded sulfate with a smaller MIF signature. One likely MIF mechanism is intramolecular disequilibrium (or non-RRKM) effects, as proposed for O + O2 -- > O3 [5]. The isoelectronic sulfur reaction, S + S2 --> S3, may also exhibit non-RRKM effects, but for several reasons that I will discuss such effects may either be reduced in magnitude or of negligible importance. A second possible source of MIF is isotope-selective photodissociation during predissociation. This process is likely in SO and SH, may occur in SO2, and unlikely in H2S, but in all cases depends on wavelength. SO2 dissociation is also likely to depend on the oxygen isotopes present, because an O isotope substitution will change SO2 symmetry. Although this may produce a MIF signature in oxygen isotopes, it's not clear that this would be accompanied by a MIF effect in S. I will present kinetics simulations of the above H2S and SO2 photolysis experiments, and show how it is possible to use the results of these experiments to constrain the mechanism of MIF for atmospheric sulfur species. For example, simulations of Sel formation by H2S photolysis predict little MIF in experiments, but possible MIF in the atmosphere. [1] J. Farquhar et al. (2000) Science 289 756-758. [2] J. Farquhar et al. (2000) Nature

  20. Determination of organic compounds from wood combustion aerosol nanoparticles by different gas chromatographic systems and by aerosol mass spectrometry.

    PubMed

    Laitinen, Totti; Martín, Sara Herrero; Parshintsev, Jevgeni; Hyötyläinen, Tuulia; Hartonen, Kari; Riekkola, Marja-Liisa; Kulmala, Markku; Pavón, José Luis Pérez

    2010-01-01

    Organic compounds in atmospheric nanoparticles have an effect on human health and the climate. The determination of these particles is challenged by the difficulty of sampling, the complexity of sample composition, and the trace-level concentrations of the compounds. Meeting the challenge requires the development of sophisticated sampling systems for size-resolved particles and the optimization of sensitive, accurate and simple analytical techniques and methods. A new sampling system is proposed where particles are charged with a bipolar charger and size-segregated with a differential mobility analyzer. This system was successfully used to sample particles from wood pyrolysis with particle sizes 30-100nm. Particles were analyzed by four techniques: comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry, gas chromatography-time-of-flight mass spectrometry, gas chromatography-quadrupole mass spectrometry, and aerosol mass spectrometry (aerosol MS). In the chromatographic techniques, particles were collected on a filter and analyzed off-line after sample preparation, whereas in the aerosol MS, particle analysis was performed directly from the particle source. Target compounds of the samples were polyaromatic hydrocarbons and n-alkanes. The analytical techniques were compared and their advantages and disadvantages were evaluated. The sampling system operated well and target compounds were identified in low concentrations. PMID:19945113

  1. AMS Measurements in National Parks of Aerosol Mass, Size and Composition, Comparison with Filter Samples and Correlation with Particle Hygroscopicity and Optical Extinction Properties

    NASA Astrophysics Data System (ADS)

    Alexander, M.; Taylor, N. F.; Collins, D. R.; Kumar, N.; Allen, J.; Newburn, M.; Lowenthal, D. H.; Zielinska, B.

    2011-12-01

    We report a comparison of results from aerosol studies at Great Smoky Mountain National Park (2006), Mt. Rainier National Park (2009) and Acadia National Park (2011), all class I visibility areas associated with IMPROVE (Interagency Monitoring of Protected Visual Environments) sites. This collaborative study was sponsored by the Electric Power Research Institute (EPRI) and was done with the cooperation of the National Park Service and the EPA. The atmospheric aerosol composition in these sites is influenced by a number of anthropogenic as well as biogenic sources, providing a rich environment for fundamental aerosol studies. The primary purpose of these studies was to add state-of-the-art aerosol instrumentation to the standard light extinction and aerosol measurements at the site, used to determine parameters for the IMPROVE light extinction reconstruction equation, adopted by the EPA to estimate light extinction from atmospheric aerosol concentrations and Rayleigh scattering. The combination of these diverse measurements also provides significant insight into fundamental aerosol properties such as aging and radiative forcing. New instrumentation included a quadrupole aerosol mass spectrometer (Aerodyne Q-AMS-Smoky Mountain Study), a high resolution aerosol time-of-flight mass spectrometer (Aerodyne HR-ToF-AMS - Mt. Rainier and Acadia studies) for real time measurements that directly address the relationship between sulfate, nitrate, and OC size and concentration, which is related to cloud and dry gas-to-particle conversion as air masses age during transport, the relationship between WSOC hygroscopic growth and oxygenated organic (OOA) composition, the OCM/OC ratio, and the chemical composition that determines the ambient hygroscopic state. The OCM/OC ratio and organic water uptake was addressed with high-volume and medium volume PM2.5 aerosol samples. Aerosols were collected daily on Teflon coated glass fiber filters (TGFF) in four high-volume PM2.5 samplers

  2. Levels and Speciation of Platinum in Size-Fractionated Atmospheric Aerosol in Urban and Rural Sites across Europe

    NASA Astrophysics Data System (ADS)

    Shafer, Martin; Antkiewicz, Dagmara; Overdier, Joel; Schauer, James

    2016-04-01

    In this study we characterized the levels and speciation of platinum in a unique set of size-resolved atmospheric aerosol (PM) samples obtained from urban environments across Europe. From April-July 2012 we collected PM from roadside canyon, roadside motorway, and background urban sites in each of six European cities (Amsterdam, Frankfurt, London, Milan, Stockholm, and Thessaloniki). A Hi-Vol sampler was used to collect PM in three size classes (>PM7, PM7-PM3, PM3) and characterized for total platinum, soluble platinum (in a suite of physiologically relevant fluids - lung fluid (ALF), Gambles saline, 0.07M HCl, and MQ) and speciated forms (colloidal and anionic) within the soluble fractions. In addition we measured 50 other elements by SF-ICPMS, soluble ions by IC, and soluble organic carbon in the PM. Order-of-magnitude differences in air concentrations of total platinum were observed between urban sites, ranging from 4 to over 45 pg/m3; with a median level of 6 pg/m3. When platinum concentrations are normalized to PM mass the cross Europe and site-to-site variability was substantially reduced - a 3-fold variation from 200 to 600 ng/g was observed. Roadside canyon sites in London, Stockholm and Thessaloniki exhibited the highest concentrations; however levels at urban background sites were remarkably similar across the cities. Relatively consistent and low concentrations (1 to 2 pg/m3) of total platinum were observed at rural background sites across Europe. The contribution of coarse particles (>7 micron and 7-3 micron) to air concentrations of total platinum was very significant (>35% at nearly all sites). Soluble platinum fractions ranged from 2 to 6% (MQ to HCl) in rural background sites to 5 to 20% (MQ to HCl) in roadway canyon sites in London and Thessaloniki; with the extractable platinum fractions a strong function of pH. With the exception of urban canyon sites in London and Thessaloniki, soluble platinum concentrations in the fine aerosol (PM3) were all

  3. Mass size distributions of soluble sulfate, nitrate and ammonium in the Madrid urban aerosol

    NASA Astrophysics Data System (ADS)

    Plaza, J.; Pujadas, M.; Gómez-Moreno, F. J.; Sánchez, M.; Artíñano, B.

    2011-09-01

    This paper analyzes the mass size distribution of some inorganic species present in the atmospheric aerosol from a field campaign carried out in Madrid throughout a complete year (February 2007-February 2008). Samplings were performed by means of a micro-orifice uniform deposit impactor (MOUDI). Ambient air was sampled during consecutive nocturnal and diurnal periods, and diurnal/nocturnal behaviors were compared for the twenty night-day sampling pairs that were gathered. Annual and seasonal averages were obtained, and some case studies under specific atmospheric conditions are discussed in the paper. Results have shown that the sulfate and ammonium mass was concentrated in the accumulation mode, between 0.18 and 0.56 μm, so that gas-phase and condensation processes for secondary aerosol formation prevailed during the sampling periods in this area. An exception to this behavior was found during a fog event when distributions for these two species were centered in the 0.56-1 and 1-1.8 μm size stages, corresponding to the droplet mode. In most of the samples, the ammonium mass measured in these size ranges was enough or almost enough to neutralize inorganic acidity by formation of ammonium sulfate and nitrate. However, a significant sulfate mass not neutralized by ammonium was found in the impactor backup quartz filter (aerodynamic diameter < 0.056 μm). The concentration of this sulfate and its contribution to the ultrafine fraction mass was higher under good dispersive conditions, prevailing in summer, when particle growth processes are not so favored due to the higher atmospheric dilution factors. The origin of this ultrafine sulfate has been attributed to direct emissions from traffic, associated to the nucleation mode. Regarding the nitrate concentration, it was found higher in the coarse mode than in the accumulation mode on an annual basis. The highest concentrations were measured in winter episodic situations. The marked seasonal variability shown in the

  4. Progress Toward a Global, EOS-Era Aerosol Air Mass Type Climatology

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph A.

    2012-01-01

    The MISR and MODIS instruments aboard the NASA Earth Observing System's Terra Satellite have been collecting data containing information about the state of Earth's atmosphere and surface for over eleven years. Data from these instruments have been used to develop a global, monthly climatology of aerosol amount that is widely used as a constraint on climate models, including those used for the 2007 IPCC assessment report. The next frontier in assessing aerosol radiative forcing of climate is aerosol type, and in particular, the absorption properties of major aerosol air masses. This presentation will focus on the prospects for constraining aerosol type globally, and the steps we are taking to apply a combination of satellite and suborbital data to this challenge.

  5. Lightning and Mass Independent Oxygen Isotopic Fractionation in Nebular Silicates

    NASA Technical Reports Server (NTRS)

    Nuth, Joseph A.

    2009-01-01

    Lightning has long been postulated as the agent of Chondru|e formation in the solar nebula, but it may have an additional role to play as well. Lightning bolts of almost any scale will both vaporize dust and liberate oxygen atoms that will then interact with both nebular gases as well as the refractory silicate vapor as it re-condenses. Such processes should result in the addition of the heavy oxygen isotopes to the growing silicate grains while the light oxygen-16 becomes part of the gas phase water. This process will proceed to some extent throughout the history of any turbulent nebula and will result in the gradual increase of O-16 in the gas phase and in a much larger relative increase in the O-17 and O-18 content of the nebular dust. Laboratory experiments have demonstrated the production of such "heavy oxygen enriched", non-mass-dependently-fractionated dust grains in a high voltage discharge in a hydrogen rich gas containing small quantities of silane, pentacarbonyl iron and oxygen.

  6. Calculating the mass fraction of primordial black holes

    SciTech Connect

    Young, Sam; Byrnes, Christian T.; Sasaki, Misao E-mail: ctb22@sussex.ac.uk

    2014-07-01

    We reinspect the calculation for the mass fraction of primordial black holes (PBHs) which are formed from primordial perturbations, finding that performing the calculation using the comoving curvature perturbation R{sub c} in the standard way vastly overestimates the number of PBHs, by many orders of magnitude. This is because PBHs form shortly after horizon entry, meaning modes significantly larger than the PBH are unobservable and should not affect whether a PBH forms or not—this important effect is not taken into account by smoothing the distribution in the standard fashion. We discuss alternative methods and argue that the density contrast, Δ, should be used instead as super-horizon modes are damped by a factor k{sup 2}. We make a comparison between using a Press-Schechter approach and peaks theory, finding that the two are in close agreement in the region of interest. We also investigate the effect of varying the spectral index, and the running of the spectral index, on the abundance of primordial black holes.

  7. High-Resolution Mass Spectroscopic Analysis of Secondary Organic Aerosol Generated by Ozonolysis of Isoprene

    SciTech Connect

    Nguyen, Tran B; Bateman, Adam P; Bones, David L; Nizkorodov, Serguei; Laskin, Julia; Laskin, Alexander

    2010-02-01

    The chemical composition of secondary organic aerosol (SOA) generated from the ozonolysis of isoprene (C5H8) in the presence of an OH scavenger was examined using high-resolution electrospray ionization mass spectrometry (ESI-MS). The chemical composition of SOA is complex, with more than 1000 assigned peaks observed in the positive and negative ion mode spectra. Only a small fraction of peaks corresponds to known products of isoprene oxidation, such as pyruvic acid, glycolic acid, methylglyoxal, etc. The absolute majority of the detected peaks correspond to highly oxidized oligomeric constituents of SOA, with an average O:C molar ratio of ~0.6. The corresponding organic mass (OM) to organic oxygen (OO) ratio is OM/OO ~2.4. Approximately 8% of oxygen atoms in SOA are in the form of peroxides as quantified with an iodide test. Double bond equivalency (DBE) factors, representing the sum of all double bonds and rings, increase by 1 for every 2-3 additional carbon atoms in the molecule. The prevalent oligomer building blocks are therefore carbonyls or carboxylic acids with a C2-C3 skeleton. Kendrick analysis suggests that simple aldehydes, specifically formaldehyde, acetaldehyde, and methylglyoxal can serve as monomeric building blocks in the observed oligomers. The large number of reactive functional groups, especially organic peroxides and carbonyls, suggests that isoprene/O3 SOA should be prone to chemical and photochemical aging.

  8. Criteria for significance of simultaneous presence of both condensible vapors and aerosol particles on mass transfer (deposition) rates

    NASA Technical Reports Server (NTRS)

    Gokoglu, S. A.

    1986-01-01

    The simultaneous presence of aerosol particles and condensible vapors in a saturated boundary layer which may affect deposition rates to subcooled surfaces because of vapor-particle interactions is discussed. Scavenging of condensible vapors by aerosol particles may lead to increased particle size and decreased vapor mass fraction, which alters both vapor and particle deposition rates. Particles, if sufficiently concentrated, may also coagulate. Criteria are provided to assess the significance of such phenomena when particles are already present in the mainstream and are not created inside the boundary layer via homogeneous nucleation. It is determined that there is direct proportionality with: (1) the mass concentration of both condensible vapors and aerosol particles; and (2) the square of the boundary layer thickness to particle diameter ratio (delta d sub p) square. Inverse proportionality was found for mainstream to surface temperature difference if thermophoresis dominates particle transport. It is concluded that the square of the boundary layer thickness to particle diameter ratio is the most critical factor to consider in deciding when to neglect vapor-particle interactions.

  9. Identification of aerosol types over an urban site based on air-mass trajectory classification

    NASA Astrophysics Data System (ADS)

    Pawar, G. V.; Devara, P. C. S.; Aher, G. R.

    2015-10-01

    Columnar aerosol properties retrieved from MICROTOPS II Sun Photometer measurements during 2010-2013 over Pune (18°32‧N; 73°49‧E, 559 m amsl), a tropical urban station in India, are analyzed to identify aerosol types in the atmospheric column. Identification/classification is carried out on the basis of dominant airflow patterns, and the method of discrimination of aerosol types on the basis of relation between aerosol optical depth (AOD500 nm) and Ångström exponent (AE, α). Five potential advection pathways viz., NW/N, SW/S, N, SE/E and L have been identified over the observing site by employing the NOAA-HYSPLIT air mass back trajectory analysis. Based on AE against AOD500 nm scatter plot and advection pathways followed five major aerosol types viz., continental average (CA), marine continental average (MCA), urban/industrial and biomass burning (UB), desert dust (DD) and indeterminate or mixed type (MT) have been identified. In winter, sector SE/E, a representative of air masses traversed over Bay of Bengal and Eastern continental Indian region has relatively small AOD (τpλ = 0.43 ± 0.13) and high AE (α = 1.19 ± 0.15). These values imply the presence of accumulation/sub-micron size anthropogenic aerosols. During pre-monsoon, aerosols from the NW/N sector have high AOD (τpλ = 0.61 ± 0.21), and low AE (α = 0.54 ± 0.14) indicating an increase in the loading of coarse-mode particles over Pune. Dominance of UB type in winter season for all the years (i.e. 2010-2013) may be attributed to both local/transported aerosols. During pre-monsoon seasons, MT is the dominant aerosol type followed by UB and DD, while the background aerosols are insignificant.

  10. 40 CFR Table 5 to Subpart Qqqq of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 12 2011-07-01 2009-07-01 true Default Organic HAP Mass Fraction for... HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the.... Solvent/solvent blend CAS. No. Average organic HAP mass fraction Typical organic HAP, percent by mass...

  11. 40 CFR Table 5 to Subpart Oooo of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 12 2011-07-01 2009-07-01 true Default Organic HAP Mass Fraction for... 63—Default Organic HAP Mass Fraction for Petroleum Solvent Groups a You may use the mass fraction... formulation data: Solvent type Averageorganic HAP mass fraction Typical organic HAP, percent by mass...

  12. 40 CFR Table 3 to Subpart Nnnn of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 12 2011-07-01 2009-07-01 true Default Organic HAP Mass Fraction for... Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following.../solvent blend CAS. No. Average organic HAP mass fraction Typical organic HAP, percent by mass 1....

  13. 40 CFR Table 4 to Subpart IIIi of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 12 2011-07-01 2009-07-01 true Default Organic HAP Mass Fraction for... Organic HAP Mass Fraction for Petroleum Solvent Groups a You may use the mass fraction values in the... Solvent type Averageorganic HAP mass fraction Typical organic HAP, percent by mass Aliphatic b 0.03...

  14. 40 CFR Table 6 to Subpart Qqqq of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 12 2011-07-01 2009-07-01 true Default Organic HAP Mass Fraction for... HAP Mass Fraction for Petroleum Solvent Groups a You may use the mass fraction values in the following... type Average organic HAP mass fraction Typical organic HAP, percent by mass Aliphatic b 0.03 1%...

  15. 40 CFR Table 4 to Subpart Pppp of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 12 2011-07-01 2009-07-01 true Default Organic HAP Mass Fraction for... Organic HAP Mass Fraction for Petroleum Solvent Groups a You may use the mass fraction values in the.... Solvent type Averageorganic HAP mass fraction Typical organic HAP, percent by mass Aliphatic b 0.03...

  16. 40 CFR Table 4 to Subpart Nnnn of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 12 2011-07-01 2009-07-01 true Default Organic HAP Mass Fraction for... Mass Fraction for Petroleum Solvent Groups a You may use the mass fraction values in the following... type Average organic HAP mass fraction Typical organic HAP, percent by mass Aliphatic b 0.03 1%...

  17. 40 CFR Table 3 to Subpart IIIi of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 12 2011-07-01 2009-07-01 true Default Organic HAP Mass Fraction for... Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the... Solvent/solvent blend CAS. No. Averageorganic HAP mass fraction Typical organic HAP, percent by mass...

  18. 40 CFR Table 3 to Subpart Rrrr of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 13 2012-07-01 2012-07-01 false Default Organic HAP Mass Fraction for... Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the...: Solvent/Solvent blend CAS. No. Average organic HAP mass fraction Typical organic HAP, percent by mass...

  19. 40 CFR Table 4 to Subpart Pppp of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 13 2013-07-01 2012-07-01 true Default Organic HAP Mass Fraction for... 63—Default Organic HAP Mass Fraction for Petroleum Solvent Groups a You may use the mass fraction... formulation data. Solvent type Averageorganic HAP mass fraction Typical organic HAP, percent by mass...

  20. 40 CFR Table 4 to Subpart Rrrr of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups 1

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 13 2012-07-01 2012-07-01 false Default Organic HAP Mass Fraction for... Organic HAP Mass Fraction for Petroleum Solvent Groups 1 You May Use the Mass Fraction Values in the...: Solvent type Average organic HAP mass fraction Typical organic percent HAP, by mass Aliphatic 2 0.03...

  1. 40 CFR Table 7 to Subpart Kkkk of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 13 2012-07-01 2012-07-01 false Default Organic HAP Mass Fraction for... Organic HAP Mass Fraction for Petroleum Solvent Groups a You may use the mass fraction values in the.... Solvent type Averageorganic HAP mass fraction Typicalorganic HAP, percent by mass Aliphatic b 0.03...

  2. 40 CFR Table 3 to Subpart Rrrr of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 13 2013-07-01 2012-07-01 true Default Organic HAP Mass Fraction for... Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the...: Solvent/Solvent blend CAS. No. Average organic HAP mass fraction Typical organic HAP, percent by mass...

  3. 40 CFR Table 4 to Subpart Pppp of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 13 2012-07-01 2012-07-01 false Default Organic HAP Mass Fraction for... 63—Default Organic HAP Mass Fraction for Petroleum Solvent Groups a You may use the mass fraction... formulation data. Solvent type Averageorganic HAP mass fraction Typical organic HAP, percent by mass...

  4. 40 CFR Table 6 to Subpart Kkkk of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 13 2014-07-01 2014-07-01 false Default Organic HAP Mass Fraction for... Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the.... Solvent/solvent blend CAS. No. Averageorganic HAP mass fraction Typical organic HAP, percent by mass...

  5. 40 CFR Table 6 to Subpart Kkkk of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 13 2013-07-01 2012-07-01 true Default Organic HAP Mass Fraction for... Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the.... Solvent/solvent blend CAS. No. Averageorganic HAP mass fraction Typical organic HAP, percent by mass...

  6. 40 CFR Table 6 to Subpart Kkkk of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 13 2012-07-01 2012-07-01 false Default Organic HAP Mass Fraction for... Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the.... Solvent/solvent blend CAS. No. Averageorganic HAP mass fraction Typical organic HAP, percent by mass...

  7. 40 CFR Table 4 to Subpart Rrrr of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups 1

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 13 2013-07-01 2012-07-01 true Default Organic HAP Mass Fraction for... Organic HAP Mass Fraction for Petroleum Solvent Groups 1 You May Use the Mass Fraction Values in the...: Solvent type Average organic HAP mass fraction Typical organic percent HAP, by mass Aliphatic 2 0.03...

  8. 40 CFR Table 7 to Subpart Kkkk of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 13 2013-07-01 2012-07-01 true Default Organic HAP Mass Fraction for... Organic HAP Mass Fraction for Petroleum Solvent Groups a You may use the mass fraction values in the.... Solvent type Averageorganic HAP mass fraction Typicalorganic HAP, percent by mass Aliphatic b 0.03...

  9. 40 CFR Table 3 to Subpart Rrrr of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 13 2014-07-01 2014-07-01 false Default Organic HAP Mass Fraction for... Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the...: Solvent/Solvent blend CAS. No. Average organic HAP mass fraction Typical organic HAP, percent by mass...

  10. 40 CFR Table 4 to Subpart IIIi of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Default Organic HAP Mass Fraction for... Organic HAP Mass Fraction for Petroleum Solvent Groups a You may use the mass fraction values in the... Solvent type Averageorganic HAP mass fraction Typical organic HAP, percent by mass Aliphatic b 0.03...

  11. 40 CFR Table 5 to Subpart Qqqq of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Default Organic HAP Mass Fraction for... HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the.... Solvent/solvent blend CAS. No. Average organic HAP mass fraction Typical organic HAP, percent by mass...

  12. 40 CFR Table 3 to Subpart IIIi of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Default Organic HAP Mass Fraction for... Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the... Solvent/solvent blend CAS. No. Averageorganic HAP mass fraction Typical organic HAP, percent by mass...

  13. 40 CFR Table 3 to Subpart Nnnn of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Default Organic HAP Mass Fraction for... Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following.../solvent blend CAS. No. Average organic HAP mass fraction Typical organic HAP, percent by mass 1....

  14. 40 CFR Table 4 to Subpart Pppp of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Default Organic HAP Mass Fraction for... Organic HAP Mass Fraction for Petroleum Solvent Groups a You may use the mass fraction values in the.... Solvent type Averageorganic HAP mass fraction Typical organic HAP, percent by mass Aliphatic b 0.03...

  15. Aerosol composition at Chacaltaya, Bolivia, as determined by size-fractionated sampling

    NASA Astrophysics Data System (ADS)

    Adams, F.; van Espen, P.; Maenhaut, W.

    Thirty-four cascade-impactor samples were collected between September 1977 and November 1978 at Chacaltaya, Bolivia. The concentrations of 25 elements were measured for the six impaction stages of each sample by means of energy-dispersive X-ray fluorescence and proton-induced X-ray emission analysis. The results indicated that most elements are predominantly associated with a unimodal coarse-particle soil-dustdispersion component. Also chlorine and the alkali and alkaline earth elements belong to this group. The anomalously enriched elements (S, Br and the heavy metals Cu, Zn, Ga, As, Se, Pb and Bi) showed a bimodal size distribution. Correlation coefficient calculations and principal component analysis indicated the presence in the submicrometer aerosol mode of an important component, containing S, K, Zn, As and Br, which may originate from biomass burning. For certain enriched elements (i.e. Zn and perhaps Cu) the coarse-particle enrichments observed may be the result of the true crust-air fractionation during soil-dust dispersion.

  16. Elemental composition of size-fractionated urban aerosol collected in Florence, Italy; preliminary results

    NASA Astrophysics Data System (ADS)

    Del Carmine, P.; Lucarelli, F.; Mandò, P. A.; Valerio, M.; Prati, P.; Zucchiatti, A.

    1999-04-01

    An extensive investigation is in progress aiming at the characterisation of the air particulate composition in Florence. We present here the preliminary results concerning the analysis of size-fractionated aerosol samples taken by two-stage streaker samplers in two sites characterised by different urban settings (one in a heavy traffic area, one in a green area). The sampling period (21 January-22 February) includes two days during which the Municipality of Florence has banned the circulation of non-catalytic cars, due to the increase of NO 2 above the "recommended safety values". Hourly concentrations of 20 elements from Na to Pb were determined using the external beam PIXE facility of the I.N.F.N. Van de Graaff accelerator at the Physics Department of the Florence University. Factor analysis on the data set confirms that traffic is the main source of atmospheric pollution in Florence. The ban of non-catalytic cars seems to have produced no effect on the concentration of detected elements (in particular Pb and Br).

  17. Evolution of organic aerosol mass spectra upon heating: implications for OA phase and partitioning behavior

    NASA Astrophysics Data System (ADS)

    Cappa, C. D.; Wilson, K. R.

    2011-03-01

    Vacuum Ultraviolet (VUV) photoionization mass spectrometry has been used to measure the evolution of chemical composition for two distinct organic aerosol types as they are passed through a thermodenuder at different temperatures. The two organic aerosol types considered are primary lubricating oil (LO) aerosol and secondary aerosol from the α-pinene + O3 reaction (αP). The evolution of the VUV mass spectra for the two aerosol types with temperature are observed to differ dramatically. For LO particles, the spectra exhibit distinct changes with temperature in which the lower m/z peaks, corresponding to compounds with higher vapor pressures, disappear more rapidly than the high m/z peaks. In contrast, the αP aerosol spectrum is essentially unchanged by temperature even though the particles experience significant mass loss due to evaporation. The variations in the LO spectra are found to be quantitatively in agreement with expectations from absorptive partitioning theory whereas the αP spectra suggest that the evaporation of αP derived aerosol appears to not be governed by partitioning theory. We postulate that this difference arises from diffusivity within the αP particles being sufficiently slow that they do not exhibit the expected liquid-like behavior and perhaps exist in a glassy state. To reconcile these observations with decades of aerosol growth measurements, which indicate that OA formation is described by equilibrium partitioning, we present a conceptual model wherein the secondary OA is formed and then rapidly converted from an absorbing form to a non-absorbing form. The results suggest that, although OA growth may be describable by equilibrium partitioning theory, the properties of organic aerosol once formed may differ significantly from the properties determined in the equilibrium framework.

  18. Evolution of organic aerosol mass spectra upon heating: implications for OA phase and partitioning behavior

    NASA Astrophysics Data System (ADS)

    Cappa, C. D.; Wilson, K. R.

    2010-11-01

    Vacuum Ultraviolet (VUV) photoionization mass spectrometry has been used to measure the evolution of chemical composition for two distinct organic aerosol types as they are passed through a thermodenuder at different temperatures. The two organic aerosol types considered are primary lubricating oil (LO) aerosol and secondary aerosol from the α-pinene + O3 reaction (αP). The evolution of the VUV mass spectra for the two aerosol types with temperature are observed to differ dramatically. For LO particles, the spectra exhibit distinct changes with temperature in which the lower m/z peaks, corresponding to compounds with higher vapor pressures, disappear more rapidly than the high m/z peaks. In contrast, the αP aerosol spectrum is essentially unchanged by temperature even though the particles experience significant mass loss due to evaporation. The variations in the LO spectra are found to be quantitatively in agreement with expectations from absorptive partitioning theory whereas the αP spectra suggest that the evaporation of αP derived aerosol appears to not be governed by partitioning theory. We postulate that this difference arises from the αP particles existing as in a glassy state instead of having the expected liquid-like behavior. To reconcile these observations with decades of aerosol growth measurements, which indicate that OA formation is described by equilibrium partitioning, we present a conceptual model wherein the secondary OA is formed and then rapidly converted from an absorbing form to a non-absorbing form. The results suggest that although OA growth may be describable by equilibrium partitioning theory, the properties of organic aerosol once formed may differ significantly from the properties determined in the equilibrium framework.

  19. Evolution of organic aerosol mass spectra upon heating: implications for OA phase and partitioning behavior

    SciTech Connect

    UC Davis; Cappa, Christopher D.; Wilson, Kevin R.

    2010-10-28

    Vacuum Ultraviolet (VUV) photoionization mass spectrometry has been used to measure the evolution of chemical composition for two distinct organic aerosol types as they are passed through a thermodenuder at different temperatures. The two organic aerosol types considered are primary lubricating oil (LO) aerosol and secondary aerosol from the alpha-pinene + O3 reaction (alphaP). The evolution of the VUV mass spectra for the two aerosol types with temperature are observed to differ dramatically. For LO particles, the spectra exhibit distinct changes with temperature in which the lower m/z peaks, corresponding to compounds with higher vapor pressures, disappear more rapidly than the high m/z peaks. In contrast, the alphaP aerosol spectrum is essentially unchanged by temperature even though the particles experience significant mass loss due to evaporation. The variations in the LO spectra are found to be quantitatively in agreement with expectations from absorptive partitioning theory whereas the alphaP spectra suggest that the evaporation of alphaP derived aerosol appears to not be governed by partitioning theory. We postulate that this difference arises from the alphaP particles existing as in a glassy state instead of having the expected liquid-like behavior. To reconcile these observations with decades of aerosol growth measurements, which indicate that OA formation is described by equilibrium partitioning, we present a conceptual model wherein the secondary OA is formed and then rapidly converted from an absorbing form to a non-absorbing form. The results suggest that although OA growth may be describable by equilibrium partitioning theory, the properties of organic aerosol once formed may differ significantly from the properties determined in the equilibrium framework.

  20. Fast Airborne Aerosol Size and Chemistry Measurements with the High Resolution Aerosol Mass Spectrometer during the MILAGRO Campaign

    NASA Technical Reports Server (NTRS)

    DeCarlo, P. F.; Dunlea, E. J.; Kimmel, J. R.; Aiken, A. C.; Sueper, D.; Crounse, J.; Wennberg, P. O.; Emmons, L.; Shinozuka, Y.; Clarke, A.; Zhou, J.; Tomlinson, J.; Collins,D. R.; Knapp, D.; Weinheimer, A. J.; Montzka,D. D.; Campos,T.; Jimenez, J. L.

    2007-01-01

    The concentration, size, and composition of non-refractory submicron aerosol (NR-PM(sub l)) was measured over Mexico City and central Mexico with a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) onboard the NSF/NCAR C-130 aircraft as part of the MILAGRO field campaign. This was the first aircraft deployment of the HR-ToF-AMS. During the campaign the instrument performed very well, and provided 12 s data. The aerosol mass from the AMS correlates strongly with other aerosol measurements on board the aircraft. Organic aerosol (OA) species dominate the NR-PM(sub l) mass. OA correlates strongly with CO and HCN indicating that pollution (mostly secondary OA, SOA) and biomass burning (BB) are the main OA sources. The OA to CO ratio indicates a typical value for aged air of around 80 microg/cubic m (STP) ppm(exp -1). This is within the range observed in outflow from the Northeastern US, which could be due to a compensating effect between higher BB but lower biogenic VOC emissions during this study. The O/C atomic ratio for OA is calculated from the HR mass spectra and shows a clear increase with photochemical age, as SOA forms rapidly and quickly overwhelms primary urban OA, consistent with Volkamer et al. (2006) and Kleinman et al. (2008). The stability of the OA/CO while O/C increases with photochemical age implies a net loss of carbon from the OA. BB OA is marked by signals at m/z 60 and 73, and also by a signal enhancement at large m/z indicative of larger molecules or more resistance to fragmentation. The main inorganic components show different spatial patterns and size distributions. Sulfate is regional in nature with clear volcanic and petrochemical/power plant sources, while the urban area is not a major regional source for this species. Nitrate is enhanced significantly in the urban area and immediate outflow, and is strongly correlated with CO indicating a strong urban source. The importance of nitrate decreases with distance from the city

  1. A new method for assessing the contribution of Primary Biological Atmospheric Particles to the mass concentration of the atmospheric aerosol.

    PubMed

    Perrino, Cinzia; Marcovecchio, Francesca

    2016-02-01

    Primary Biologic Atmospheric Particles (PBAPs) constitute an interesting and poorly investigated component of the atmospheric aerosol. We have developed and validated a method for evaluating the contribution of overall PBAPs to the mass concentration of atmospheric particulate matter (PM). The method is based on PM sampling on polycarbonate filters, staining of the collected particles with propidium iodide, observation at epifluorescence microscope and calculation of the bioaerosol mass using a digital image analysis software. The method has been also adapted to the observation and quantification of size-segregated aerosol samples collected by multi-stage impactors. Each step of the procedure has been individually validated. The relative repeatability of the method, calculated on 10 pairs of atmospheric PM samples collected side-by-side, was 16%. The method has been applied to real atmospheric samples collected in the vicinity of Rome, Italy. Size distribution measurements revealed that PBAPs was mainly in the coarse fraction of PM, with maxima in the range 5.6-10 μm. 24-h samples collected during different period of the year have shown that the concentration of bioaerosol was in the range 0.18-5.3 μg m(-3) (N=20), with a contribution to the organic matter in PM10 in the range 0.5-31% and to the total mass concentration of PM10 in the range 0.3-18%. The possibility to determine the concentration of total PBAPs in PM opens up interesting perspectives in terms of studying the health effects of these components and of increasing our knowledge about the composition of the organic fraction of the atmospheric aerosol. PMID:26680730

  2. Single Particle Fluorescence & Mass Spectrometry for the Detection of Biological Aerosols

    SciTech Connect

    Coffee, K; Riot, V; Woods, B; Steele, P; Gard, E E

    2005-04-25

    Biological Aerosol Mass Spectrometry (BAMS) is an emerging technique for the detection of biological aerosols, which is being developed at Lawrence Livermore National Laboratory. The current system uses several orthogonal analytical methods to improve system selectivity, sensitivity and speed in order to maximize its utility as a biological aerosol detection system with extremely low probability of false alarm and high probability of detection. Our approach is to pre-select particles of interest by size and fluorescence prior to mass spectral analysis. The ability to distinguish biological aerosols from background and to discriminate bacterial spores, vegetative cells, viruses and toxins from one another will be shown. Data from particle standards of known chemical composition will be discussed. Analysis of ambient particles will also be presented.

  3. Influence of air mass origin on aerosol properties at a remote Michigan forest site

    NASA Astrophysics Data System (ADS)

    VanReken, T. M.; Mwaniki, G. R.; Wallace, H. W.; Pressley, S. N.; Erickson, M. H.; Jobson, B. T.; Lamb, B. K.

    2015-04-01

    The northern Great Lakes region of North America is a large, relatively pristine area. To date, there has only been limited study of the atmospheric aerosol in this region. During summer 2009, a detailed characterization of the atmospheric aerosol was conducted at the University of Michigan Biological Station (UMBS) as part of the Community Atmosphere-Biosphere Interactions Experiment (CABINEX). Measurements included particle size distribution, water-soluble composition, and CCN activity. Aerosol properties were strongly dependent on the origin of the air masses reaching the site. For ∼60% of the study period, air was transported from sparsely populated regions to the northwest. During these times aerosol loadings were low, with mean number and volume concentrations of 1630 cm-3 and 1.91 μm3 cm-3, respectively. The aerosol during clean periods was dominated by organics, and exhibited low hygroscopicities (mean κ = 0.18 at s = 0.3%). When air was from more populated regions to the east and south (∼29% of the time), aerosol properties reflected a stronger anthropogenic influence, with 85% greater particle number concentrations, 2.5 times greater aerosol volume, six times more sulfate mass, and increased hygroscopicity (mean k = 0.24 at s = 0.3%). These trends are have the potential to influence forest-atmosphere interactions and should be targeted for future study.

  4. Isotopic mass independent signature of black crusts: a proxy for atmospheric aerosols formation in the Paris area (France).

    NASA Astrophysics Data System (ADS)

    Genot, Isabelle; Martin, Erwan; Yang, David Au; De Rafelis, Marc; Cartigny, Pierre; Wing, Boswell; Le Gendre, Erwann; Bekki, Slimane

    2016-04-01

    In view of the negative forcing of the sulfate aerosols on climate, a more accurate understanding of the formation of these particles is crucial. Indeed, despite the knowledge of their effects, uncertainties remain regarding the formation of sulfate aerosols, particularly the oxidation processes of S-bearing gases. Since the discovery of oxygen and sulfur mass independent fractionation (O- and S-MIF) processes on Earth, the sulfate isotopic composition became essential to investigate the atmospheric composition evolution and its consequences on the climate and the biosphere. Large amount of S-bearing compounds (SO2 mainly) is released into the atmosphere by anthropogenic and natural sources. Their oxidation in the atmosphere generates sulfate aerosols, H2SO4, which precipitate on the earth surface mainly as acid rain. One consequence of this precipitation is the formation of black crust on buildings made of carbonate stones. Indeed the chemical alteration of CaCO3 by H2SO4 leads to gypsum (CaSO4·2H2O) concretions on building walls. Associated to other particles, gypsum forms black-crusts. Therefore, black crusts acts as 'sulfate aerosol traps', meaning that their isotopic composition reveals the composition and thus the source and formation processes of sulfate aerosols in the atmosphere in a specific region. In this study we collected 37 black crusts on a 300km NW-SE profile centered on Paris (France). In our samples, sulfate represent 40wt.% and other particles 60wt.% of the black crusts. After sulfate extraction from each samples we measured their O- and S-isotopes composition. Variations of about 10‰ in δ18O and δ34S are observed and both O-MIF (Δ17O from 0 to 1.4‰) and S-MIF (Δ33S from 0 to -0.3‰) compositions have been measured. In regards to these compositions we can discuss the source and formation (oxidation pathways) of the sulfate aerosols in troposphere above the Paris region that covers urban, rural and coastal environments. Furthermore

  5. Effects of anthropogenic emissions on the molecular composition of urban organic aerosols: An ultrahigh resolution mass spectrometry study

    NASA Astrophysics Data System (ADS)

    Kourtchev, I.; O'Connor, I. P.; Giorio, C.; Fuller, S. J.; Kristensen, K.; Maenhaut, W.; Wenger, J. C.; Sodeau, J. R.; Glasius, M.; Kalberer, M.

    2014-06-01

    Identification of the organic composition of atmospheric aerosols is necessary to develop effective air pollution mitigation strategies. However, the majority of the organic aerosol mass is poorly characterized and its detailed analysis is a major analytical challenge. In this study, we applied state-of-the-art direct infusion nano-electrospray (nanoESI) ultrahigh resolution mass spectrometry (UHRMS) and liquid chromatography ESI Quadrupole Time-of-Flight (Q-TOF) MS for the analysis of the organic fraction of fine particulate matter (PM2.5) collected at an urban location in Cork, Ireland. Comprehensive mass spectral data evaluation methods (e.g., Kendrick Mass Defect and Van Krevelen) were used to identify compound classes and mass distributions of the detected species. Up to 850 elemental formulae were identified in negative mode nanoESI-UHR-MS. Nitrogen and/or sulphur containing organic species contributed up to 40% of the total identified formulae and exhibited strong diurnal variations suggesting the importance of night-time NO3 chemistry at the site. The presence of a large number of oxidised aromatic and nitroaromatic compounds in the samples indicated a strong anthropogenic influence, i.e., from traffic emissions and domestic solid fuel (DSF) burning. Most of the identified biogenic secondary organic aerosol (SOA) compounds are later-generation nitrogen- and sulphur-containing products, indicating that SOA composition is strongly affected by anthropogenic species such as NOx and SO2. Unsaturated and saturated C12-C20 fatty acids were found to be the most abundant homologs with a composition reflecting a primary marine origin. The results of this work demonstrate that the studied site is a very complex environment affected by a variety of anthropogenic activities and natural sources.

  6. Submicron aerosol analysis and organic source apportionment in an urban atmosphere in Pearl River Delta of China using high-resolution aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    He, Ling-Yan; Huang, Xiao-Feng; Xue, Lian; Hu, Min; Lin, Yun; Zheng, Jun; Zhang, Renyi; Zhang, Yuan-Hang

    2011-06-01

    The Pearl River Delta (PRD) region in South China is one of the most economically developed regions in China while also noted for its severe air pollution, especially in the urban environments. In order to understand in depth the aerosol chemistry and the emission sources in PRD, an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was deployed at an urban site in the Hong Kong-Shenzhen metropolitan area between 25 October and 2 December 2009. Ten minute-resolved measurement data were analyzed, and an average mass concentration of 44.5 ± 34.0 μg m-3 was calculated for the entire campaign. On average, organic matter was the most abundant PM1 component accounting for 39.7% of the total mass, followed by sulfate (24.5%), black carbon (measured by aethalometer, 14.0%), ammonium (10.2%), nitrate (10.0%), and chloride (1.6%). Moreover, organic matter comprised an increasing fraction of the PM1 loading as the PM1 loading increased, denoting its key role in particulate pollution in this region. Calculations of organic elemental composition based on the high-resolution organic mass spectra obtained indicated that C, H, O, and N on average contributed 33.8%, 55.1%, 10.2%, and 0.9%, respectively, to the total atomic numbers of organic aerosol (OA), which corresponded to an OM/OC ratio (the ratio of organic matter mass/organic carbon mass) of 1.57 ± 0.08. Positive matrix factorization analysis was then conducted on the high-resolution organic mass spectral data set. Four OA components were identified, including a hydrocarbon-like (HOA), a biomass burning (BBOA), and two oxygenated (LV-OOA and SV-OOA) components, which on average accounted for 29.5%, 24.1%, 18.8%, and 27.6%, respectively, of the total organic mass. The HOA was found to have contributions from both fossil fuel combustion and cooking emissions, while the BBOA was well correlated with acetonitrile, a known biomass burning marker. The LV-OOA and SV-OOA corresponded to more aged and

  7. Characterization of near-highway submicron aerosols in New York City with a high-resolution time-of-flight aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Sun, Y. L.; Zhang, Q.; Schwab, J. J.; Chen, W.-N.; Bae, M.-S.; Hung, H.-M.; Lin, Y.-C.; Ng, N. L.; Jayne, J.; Massoli, P.; Williams, L. R.; Demerjian, K. L.

    2011-11-01

    Knowledge of the variations of mass concentration, chemical composition and size distributions of submicron aerosols near roadways is of importance for reducing exposure assessment uncertainties in health effects studies. The goal of this study is to deploy and evaluate an Atmospheric Sciences Research Center-Mobile Laboratory (ASRC-ML), equipped with a suite of rapid response instruments for characterization of traffic plumes, adjacent to the Long Island Expressway (LIE) - a high-traffic highway in the New York City Metropolitan Area. In total, four measurement periods, two in the morning and two in the evening were conducted at a location approximately 30 m south of the LIE. The mass concentrations and size distributions of non-refractory submicron aerosol (NR-PM1) species were measured in situ at a time resolution of 1 min by an Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer, along with rapid measurements (down to 1 Hz) of gaseous pollutants (e.g., HCHO, NO2, NO, O3, and CO2, etc.), black carbon (BC), and particle number concentrations and size distributions. The particulate organics varied dramatically during periods with highest traffic influences from the nearby roadway. The variations were mainly observed in the hydrocarbon-like organic aerosol (HOA), a surrogate for primary OA from vehicle emissions. The inorganic species (sulfate, ammonium, and nitrate) and oxygenated OA (OOA) showed much smoother variations - with minor impacts from traffic emissions. The concentration and chemical composition of NR-PM1 also varied differently on different days depending on meteorology, traffic intensity and vehicle types. Overall, organics dominated the traffic-related NR-PM1 composition (>60%) with HOA being the major fraction of OA. The traffic-influenced organics showed two distinct modes in mass-weighted size distributions, peaking at ~120 nm and 500 nm (vacuum aerodynamic diameter, Dva), respectively. OOA and inorganic species appear to be

  8. Towards depth profiling of organic aerosols in real time using aerosol flowing atmospheric-pressure afterglow mass spectrometry (AeroFAPA-MS)

    NASA Astrophysics Data System (ADS)

    Brüggemann, Martin; Hoffmann, Thorsten

    2014-05-01

    Organic aerosol accounts for a substantial fraction of tropospheric aerosol and has implications on the earth's climate and human health. However, the characterization of its chemical composition and transformations remain a major challenge and is still connected to large uncertainties (IPCC, 2013). Recent measurements revealed that organic aerosol particles may reside in an amorphous or semi-solid phase state which impedes the diffusion within the particles (Virtanen et al., 2010; Shiraiwa et al., 2011). This means that reaction products which are formed on the surface of a particle, e.g. by OH, NO3 or ozone chemistry, cannot diffuse into the particle's core and remain at the surface. Eventually, this leads to particles with a core/shell structure. In the particles' cores the initial compounds are preserved whereas the shells contain mainly the oxidation products. By analyzing the particles' cores and shells separately, thus, it is possible to obtain valuable information on the formation and evolution of the aerosols' particle and gas phase. Here we present the development of the aerosol flowing atmospheric-pressure afterglow (AeroFAPA) technique which allows the mass spectrometric analysis of organic aerosols in real time. The AeroFAPA is an ion source based on a helium glow discharge at atmospheric pressure. The plasma produces excited helium species and primary reagent ions which are transferred into the afterglow region where the ionization of the analytes takes place. Due to temperatures of only 80 ° C to 150 ° C and ambient pressure in the afterglow region, the ionization is very soft and almost no fragmentation of organic molecules is observed. Thus, the obtained mass spectra are easy to interpret and no extensive data analysis procedure is necessary. Additionally, first results of a combination of the AeroFAPA-MS with a scanning mobility particle sizer (SMPS) suggest that it is not only possible to analyze the entire particle phase but rather that a

  9. Prospects of real-time single-particle biological aerosol analysis: A comparison between laser-induced breakdown spectroscopy and aerosol time-of-flight mass spectrometry

    NASA Astrophysics Data System (ADS)

    Beddows, D. C. S.; Telle, H. H.

    2005-08-01

    In this paper we discuss the prospects of real-time, in situ laser-induced breakdown spectroscopy applied for the identification and classification of bio-aerosols (including species of potential bio-hazard) within common urban aerosol mixtures. In particular, we address the issues associated with the picking out of bio-aerosols against common background aerosol particles, comparing laser-induced breakdown spectroscopy measurements with data from a mobile single-particle aerosol mass spectrometer (ATOFMS). The data from the latter provide statistical data over an extended period of time, highlighting the variation of the background composition. While single-particle bio-aerosols are detectable in principle, potential problems with small (˜ 1 μm size) bio-aerosols have been identified; constituents of the air mass other than background aerosols, e.g. gaseous CO 2 in conjunction with common background aerosols, may prevent unique recognition of the bio-particles. We discuss whether it is likely that laser-induced breakdown spectroscopy on its own can provide reliable, real-time identification of bio-aerosol in an urban environment, and it is suggested that more than one technique should be or would have to be used. A case for using a combination of laser-induced breakdown spectroscopy and Raman (and/or) laser-induced fluorescence spectroscopy is made.

  10. Time-of-flight aerosol mass spectrometry: Measuring gaseous iodine species after selective uptake in lab-generated aerosols

    NASA Astrophysics Data System (ADS)

    Kundel, Michael; Ries, Marco; Schott, Mathias; Hoffmann, Thorsten

    2010-05-01

    Reactive iodine species play an important role in the marine atmospheric chemistry. Recent studies show that iodine containing compounds (e.g. I2 and ICl) are involved in the tropospheric ozone depletion, the enrichment of iodine in marine aerosols and the formation of new particles in the marine boundary layer (MBL). Various laboratory and field measurements report that molecular iodine (I2) and organoiodine compounds (e.g. CH3I, CH2I2) are the most important precursors for reactive iodine in the MBL[1],[2]. However, the identification and quantification of reactive iodine containing compounds are still analytical challenges. Here, we present a new application of the time-of-flight aerosol mass spectrometer (ToF-AMS) for the quantification of gaseous I2 and ICl in real-time. Time-of-flight aerosol mass spectrometry enables the real-time analysis of the particle size, the particle mass and the chemical composition of non-refractory aerosols[3]. The aerosol enters the ToF-AMS through a critical orifice of 100 μm inner diameter. An aerodynamic lens system focuses the particles in a size range of 50-600 nm as a narrow beam into the vacuum system. While most of the air is removed by a skimmer, the particle beam is transmitted into the particle-sizing chamber. After passing the particle-sizing chamber, the non-refractory particles are flash-vaporized on a heated tungsten surface (500-600 °C) and then ionized by electron impact. The generated ions are extracted by an orthogonal extractor into the time-of-flight mass spectrometer, where the time resolved particle mass detection is performed. Since gaseous compounds are removed inside the ToF-AMS, a direct measurement of gaseous iodine species is not possible. Therefore gaseous iodine species have to be transferred from the gas phase to the particle phase before entering the ToF-AMS. For this purpose α-cyclodextrin (α-CD) particles were used as selective sampling probes for I2 and 1,3,5-trimethoxybenzene (1,3,5-TMB

  11. Chemical composition, sources, and processes of urban aerosols during summertime in Northwest China: insights from High Resolution Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Xu, J.; Zhang, Q.; Chen, M.; Ge, X.; Ren, J.; Qin, D.

    2014-06-01

    An aerodyne High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) was deployed along with a Scanning Mobility Particle Sizer (SMPS) and a Multi Angle Absorption Photometers (MAAP) to measure the temporal variations of the mass loading, chemical composition, and size distribution of sub-micrometer particulate matter (PM1) in Lanzhou, northwest China, during 12 July-7 August 2012. The average PM1 mass concentration including non-refractory PM1 (NR-PM1) measured by HR-ToF-AMS and black carbon (BC) measured by MAAP during this study was 24.5 μg m-3 (ranging from 0.86 to 105μg m-3), with a mean composition consisting of 47% organics, 16% sulfate, 12% BC, 11% ammonium, 10% nitrate, and 4% chloride. The organics was consisted of 70% carbon, 21% oxygen, 8% hydrogen, and 1% nitrogen, with the average oxygen-to-carbon ratio (O / C) of 0.33 and organic mass-to-carbon ratio (OM / OC) of 1.58. Positive matrix factorization (PMF) of the high-resolution mass spectra of organic aerosols (OA) identified four distinct factors which represent, respectively, two primary OA (POA) emission sources (traffic and food cooking) and two secondary OA (SOA) types - a fresher, semi-volatile oxygenated OA (SV-OOA) and a more aged, low-volatility oxygenated OA (LV-OOA). Traffic-related hydrocarbon-like OA (HOA) and BC displayed distinct diurnal patterns both with peak at ~07:00-11:00 (BJT: UTC +8) corresponding to the morning rush hours, while cooking OA (COA) peaked during three meal periods. The diurnal profiles of sulfate and LV-OOA displayed a broad peak between ∼07:00-15:00, while those of nitrate, ammonium, and SV-OOA showed a narrower peak at ~08:00-13:00. The later morning and early afternoon peak in the diurnal profiles of secondary aerosol species was likely caused by mixing down of pollutants aloft, which were likely produced in the residual layer decoupled from the boundary layer during night time. The mass spectrum of SV-OOA also showed similarity with that of

  12. Measurement of internal and external mixtures of test aerosols with a new Single Particle Aerosol Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Wonaschütz, Anna; Hitzenberger, Regina

    2015-04-01

    The mixing state of atmospheric aerosol particles is a very important property affecting processes such as CCN activation and scattering and absorption of light by the particles, but is challenging to determine. A new Single Particle Aerosol Mass Spectrometer (LAAPTOF, AeroMegt GmbH) was tested with regards to its capability of measuring internal and external mixture of aerosols using laboratory generated particles. To create the external mixture, solutions of three different salts in deionized water, and a suspension of carbon black (Cabot Corporation) in a mixture of isopropanol and water were nebulized and individually dried, before being passed into a small mixing chamber. To create the internal mixture, equal parts of each solution/suspension were mixed, fed into a single nebulizer, nebulized and dried. The LAAPTOF sampled from the mixing chamber and recorded mass spectra of individual particles. The analysis shows a heterogeneous ensemble of single particle spectra for the external mixture, and a homogeneous ensemble of spectra for the internal mixture. The ability of a fuzzy clustering algorithm to resolve the difference between the two mixing states was also tested.

  13. Mass Independent Fractionation of Hg Isotopes Preserved in the Precambrian

    NASA Astrophysics Data System (ADS)

    Thibodeau, A. M.; Bergquist, B. A.; Kah, L. C.; Ono, S.; Ghosh, S.; Hazen, R. M.

    2013-12-01

    Mercury (Hg) is a photochemically active, redox-sensitive, chalcophilic metal with complex biogeochemistry that displays a wide range of mass-dependent (MDF) and mass-independent (MIF) stable isotopic fractionation. In the past decade, Hg isotopes have emerged as important tracers of both the sources and cycling of Hg in the modern environment. However, their utility as environmental proxies in ancient rocks remains largely unexplored. The potential of Hg isotopes to inform Precambrian environments derives from the observation that Hg isotopes with odd atomic mass numbers (199Hg and 201Hg) undergo large MIF by the magnetic isotope effect (MIE) and smaller MIF through the nuclear volume effect (NVE). Small MIF produced via NVE has been observed for numerous transformations and is characterized by MIF ratios (Δ199Hg/Δ201Hg) of about 1.6. Large Hg-MIF driven by MIE has been observed during photochemical transformations and is characterized by Δ199Hg/Δ201Hg ratios between 1 and 1.3. This MIF signal is sensitive to a range of environmental conditions, including the amount and type of solar radiation, the presence and type of complexing organic ligands, and the Hg/dissolved organic carbon (DOC) ratio. Thus, it is hoped that Hg-MIF signals may indirectly record changes in atmospheric composition or seawater chemistry if preserved in marine sedimentary records. Previous work has clearly demonstrated that Hg-MIF signals are preserved in Archean and Paleoproterozoic marine shales and massive sulfide deposits. Here, we present evidence that such signals are also preserved in marine shales of mid-Proterozoic age, including the ~1.3 Ga Sulky formation (Dismal Lakes Group, NW Arctic), the ~1.45 Ga Greyson Shale (Belt Basin, Montana), and the ~1.5 Ga Katalsy formation (Kypry Group, Eastern European Platform). We observe that the Greyson shale and shales within the Sulky formation yield negative Hg-MIF with Δ199Hg/Δ201Hg ratios close to 1 and that Kaltasy group sediments

  14. Characterization of ambient aerosols during the Southern Oxidant and Aerosol Study (SOAS) in Centreville, AL with a high-resolution time-of-flight aerosol mass spectrometer Basak Karakurt Cevik1, Yu Jun Leong1, Carlos Hernandez1, Robert Griffin1 1 Rice University, CEE Department, 6100 Main St., Houston, TX 77005, USA

    NASA Astrophysics Data System (ADS)

    Karakurt Cevik, B.; Leong, Y.; Hernandez, C.; Griffin, R. J.

    2013-12-01

    An Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and a Brechtel Manufacturing, Inc. particle-into-liquid sampler (PILS) were deployed at a rural location in Centreville, AL, from 1 June to 15 July 2013 as a part of the Southern Oxidant and Aerosol Study (SOAS). PILS samples were analyzed with Dionex ion chromatographs. The data will allow us to characterize the temporal characteristics of the concentrations and size distributions of non-refractory (NR) chemical species in the ambient submicron particles. Preliminary analysis of the data indicates that the sub-micron particulate matter is highly dominated by organic matter with a relatively high state of oxidation and it is followed by smaller contributions from sulfate and ammonium. In order to investigate the processes and sources that lead to observed aerosol concentrations at the site, the time series will be analyzed in conjunction with additional trace gas, aerosol, and meteorological measurements. The region is known to have high biogenic volatile organic compounds (VOCs) emissions and many of these biogenic VOCs (BVOCs) are important secondary organic aerosol (SOA) precursors. Preliminary data from the HR-ToF-AMS indicates the importance of oxidized organic aerosol during SOAS. The study will also focus on the importance of the SOA in the total organic fraction and the effect of atmospheric processing on the chemical composition of the organic fraction.

  15. A rocket-borne mass analyzer for charged aerosol particles in the mesosphere

    SciTech Connect

    Knappmiller, Scott; Robertson, Scott; Sternovsky, Zoltan; Friedrich, Martin

    2008-10-15

    An electrostatic mass spectrometer for nanometer-sized charged aerosol particles in the mesosphere has been developed and tested. The analyzer is mounted on the forward end of a rocket and has a slit opening for admitting a continuous sample of air that is exhausted through ports at the sides. Within the instrument housing are two sets of four collection plates that are biased with positive and negative voltages for the collection of negative and positive aerosol particles, respectively. Each collection plate spans about an order of magnitude in mass which corresponds to a factor of 2 in radius. The number density of the charge is calculated from the current collected by the plates. The mean free path for molecular collisions in the mesosphere is comparable to the size of the instrument opening; thus, the analyzer performance is modeled by a Monte Carlo computer code that finds the aerosol particles trajectories within the instrument including both the electrostatic force and the forces from collisions of the aerosol particles with air molecules. Mass sensitivity curves obtained using the computer models are near to those obtained in the laboratory using an ion source. The first two flights of the instrument returned data showing the charge number densities of both positive and negative aerosol particles in four mass ranges.

  16. Mass-analysis of Charged Aerosol Particles in a PMSE/NLC Layer by a Rocket-borne Spectrometer

    NASA Astrophysics Data System (ADS)

    Robertson, S.; Horanyi, M.; Knappmiller, S.; Kohnert, R.; Sternovsky, Z.; Holzworth, R.; Shimogawa, M.; Friedrich, M.; Gumbel, J.; Khaplanov, M.; Megner, L.; Baumgarten, G.; Latteck, R.; Rapp, M.; Hoppe, U.

    2007-12-01

    The first of two "MASS" (Mesospheric Aerosol Sampling Spectrometer) rockets was launched from the Andoya Rocket Range at 22:51 UTC on 3 August 2007 into PMSE and NLC approximately 26 minutes after an AIM satellite overpass. The sun was 4 degrees below the horizon and the local riometer indicated that the ionospheric conditions were rather quiet, i.e., day time conditions as far as negative cluster ions are concerned. NLC were seen in the previous hour at 83 km by the ALOMAR RMR lidar pointed along the rocket trajectory and were detected at the same altitude by rocket-borne photometer measurements. The rocket carried an electrostatic mass analyzer for the charged fraction of the aerosol particles and both forward and aft deployable electric field booms. The mass analyzer was mounted on the tip of the payload and pointed in the ram direction. It has a forward inlet slit with area of 25 square centimeters and side vents for air exit. Aerosol particles with different ranges of charge-to-mass ratio are collected within the instrument housing on two sets of four biased collector plates, with one set for positive particles and one set for negative particles. A preliminary analysis of the data shows the density of negative particles with radius greater than 3 nm rising sharply at 83 and continuing to 89 km, collocated with PMSE detected by the ALWIN radar. Particles with 1-2 nm radii with both signs of charge and positive particles with less than1 nm radius were detected at 86-88 km. Initial charge-density estimates are several thousands per cubic centimeter for each of these size ranges. The E field booms detected significant potential variations in the PMSE/NLC region. Further analysis will examine in more detail the effects of aerodynamics, payload charging, and spurious charge generation by particle impacts.

  17. FRACTIONAL AEROSOL FILTRATION EFFICIENCY OF IN-DUCT VENTILATION AIR CLEANERS

    EPA Science Inventory

    The filtration efficiency of ventilation air cleaners is highly particle-size dependent over the 0.01 to 3 μm diameter size range. Current standardized test methods, which determine only overall efficiencies for ambient aerosol or other test aerosols, provide data of limited util...

  18. 40 CFR Table 4 to Subpart Oooo of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 12 2011-07-01 2009-07-01 true Default Organic HAP Mass Fraction for... 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction... formulation data. Solvent/solvent blend CAS. No. Averageorganic HAP mass fraction Typical organic HAP,...

  19. 40 CFR Table 6 to Subpart Qqqq of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 13 2013-07-01 2012-07-01 true Default Organic HAP Mass Fraction for...—Default Organic HAP Mass Fraction for Petroleum Solvent Groups a You may use the mass fraction values in... formulation data. Solvent type Average organic HAP mass fraction Typical organic HAP, percent by...

  20. 40 CFR Table 3 to Subpart Nnnn of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 13 2014-07-01 2014-07-01 false Default Organic HAP Mass Fraction for...—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in... formulation data. Solvent/solvent blend CAS. No. Average organic HAP mass fraction Typical organic...

  1. 40 CFR Table 6 to Subpart Qqqq of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 13 2012-07-01 2012-07-01 false Default Organic HAP Mass Fraction for...—Default Organic HAP Mass Fraction for Petroleum Solvent Groups a You may use the mass fraction values in... formulation data. Solvent type Average organic HAP mass fraction Typical organic HAP, percent by...

  2. 40 CFR Table 5 to Subpart Qqqq of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 13 2013-07-01 2012-07-01 true Default Organic HAP Mass Fraction for...—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in... formulation data. Solvent/solvent blend CAS. No. Average organic HAP mass fraction Typical organic...

  3. 40 CFR Table 6 to Subpart Qqqq of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 13 2014-07-01 2014-07-01 false Default Organic HAP Mass Fraction for...—Default Organic HAP Mass Fraction for Petroleum Solvent Groups a You may use the mass fraction values in... formulation data. Solvent type Average organic HAP mass fraction Typical organic HAP, percent by...

  4. 40 CFR Table 4 to Subpart Nnnn of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 13 2014-07-01 2014-07-01 false Default Organic HAP Mass Fraction for...—Default Organic HAP Mass Fraction for Petroleum Solvent Groups a You may use the mass fraction values in... formulation data. Solvent type Average organic HAP mass fraction Typical organic HAP, percent by...

  5. 40 CFR Table 3 to Subpart Nnnn of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 13 2013-07-01 2012-07-01 true Default Organic HAP Mass Fraction for...—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in... formulation data. Solvent/solvent blend CAS. No. Average organic HAP mass fraction Typical organic...

  6. 40 CFR Table 5 to Subpart Qqqq of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 13 2014-07-01 2014-07-01 false Default Organic HAP Mass Fraction for...—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in... formulation data. Solvent/solvent blend CAS. No. Average organic HAP mass fraction Typical organic...

  7. 40 CFR Table 4 to Subpart Nnnn of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 13 2012-07-01 2012-07-01 false Default Organic HAP Mass Fraction for...—Default Organic HAP Mass Fraction for Petroleum Solvent Groups a You may use the mass fraction values in... formulation data. Solvent type Average organic HAP mass fraction Typical organic HAP, percent by...

  8. 40 CFR Table 5 to Subpart Qqqq of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 13 2012-07-01 2012-07-01 false Default Organic HAP Mass Fraction for...—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in... formulation data. Solvent/solvent blend CAS. No. Average organic HAP mass fraction Typical organic...

  9. 40 CFR Table 3 to Subpart Nnnn of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 13 2012-07-01 2012-07-01 false Default Organic HAP Mass Fraction for...—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in... formulation data. Solvent/solvent blend CAS. No. Average organic HAP mass fraction Typical organic...

  10. 40 CFR Table 4 to Subpart Nnnn of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 13 2013-07-01 2012-07-01 true Default Organic HAP Mass Fraction for...—Default Organic HAP Mass Fraction for Petroleum Solvent Groups a You may use the mass fraction values in... formulation data. Solvent type Average organic HAP mass fraction Typical organic HAP, percent by...

  11. 40 CFR Table 4 to Subpart Oooo of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Default Organic HAP Mass Fraction for... 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction... formulation data. Solvent/solvent blend CAS. No. Averageorganic HAP mass fraction Typical organic HAP,...

  12. On the Interpretation of Oxygenated Organic Aerosols (and their Subtypes) Arising from Factor Analysis of Aerosol Mass Spectrometer Data

    NASA Astrophysics Data System (ADS)

    Jimenez, J. L.; Zhang, Q.; Canagaratna, M. R.; Ulbrich, I. M.; Ng, N. L.; Aiken, A. C.; Decarlo, P. F.; Kroll, J.; Mohr, C.; Allan, J. D.; Worsnop, D. R.

    2008-12-01

    Zhang et al. (ES&T 2005; ACP 2005) first performed factor analysis (FA) of Aerodyne Aerosol Mass Spectrometer (AMS) complete organic aerosol (OA) mass spectra. This study showed that an oxygenated organic aerosol (OOA) factor accounted for 2/3 of the OA mass at an urban site in Pittsburgh and strongly linked OOA to secondary organic aerosols (SOA). Many subsequent studies and the application of more powerful solution algorithms such as Positive Matrix Factorization (PMF) to the same FA problem have demonstrated the importance of OOA at most locations (e.g. Volkamer et al., GRL, 2006; Zhang et al., GRL, 2007; Lanz et al., ACP, 2007 and ES&T, 2008; Ulbrich et al., ACPD, 2008). Multiple studies have also identified several subtypes of OOA (e.g. OOA-1 and OOA-2). This type of analysis offers new insights because it provides some chemical resolution on the total OA mass with high time and size resolution, and bypasses the limitations of techniques that only analyze tracers and which may favor more reduced species. However the chemical resolution is limited and careful interpretation of the FA output is required, including the use of database spectra, time series of external tracers, tracer ratios, back-trajectory analyses, size- distribution analyses, etc. This presentation will address the interpretation of total OOA and its subfactors across a large range of locations in urban, suburban, rural, remote, and forested areas, and will compare with the results of other source apportionment techniques. Based on data from multiple datasets we conclude that (1) anthropogenic SOA in and downwind of urban areas is an important source of OOA; (2) motor vehicles, meat cooking, and trash burning are unlikely to be sources of primary OOA; (3) SOA from biogenic and biomass burning precursors are also clear sources of OOA; (4) primary biomass burning OA (P-BBOA) typically shows significant differences with ambient OOA factors; (5) heterogeneous oxidation of urban POA may give rise to

  13. Functional group composition of ambient and source organic aerosols determined by tandem mass spectrometry

    NASA Astrophysics Data System (ADS)

    Dron, J.; El Haddad, I.; Temime-Roussel, B.; Jaffrezo, J.-L.; Wortham, H.; Marchand, N.

    2010-04-01

    The functional group composition of various organic aerosols (OA) is being investigated using a recently developed analytical approach based on atmospheric pressure chemical ionisation-tandem mass spectrometry (APCI-MS/MS). The determinations of the three functional groups' contents are performed quantitatively by neutral loss (carboxylic and carbonyl groups) and precursor ion (nitro groups) scanning modes of a tandem mass spectrometer. Major organic aerosol sources are studied: vehicular emission and wood combustion for primary aerosol sources; and a secondary organic aerosol (SOA) produced through photo-oxidation of o-xylene. The results reveal significant differences in the functional group contents of these source aerosols. The laboratory generated SOA is dominated by carbonyls while carboxylics are preponderate in the wood combustion particles. On the other hand, vehicular emissions are characterised by a strong nitro content. The total amount of the three functional groups accounted for 1.7% (vehicular) to 13.5% (o-xylene photo-oxidation) of the organic carbon. The diagnostic functional group ratios are then used to tentatively differentiate sources of particles collected in an urban background environment located in an Alpine valley (Chamonix, France) during a strong winter pollution event. The three functional groups under study account for a total functionalisation rate of 2.2 to 3.8% of the organic carbon in this ambient aerosol, which is also dominated by carboxylic moieties. In this particular case study of a deep alpine valley during winter, we show that the nitro- and carbonyl-to-carboxylic diagnostic ratios can be a useful tool to distinguish the sources. In these conditions, the total OA concentrations are highly dominated by wood combustion OA. This result is confirmed by an organic markers source apportionment approach which assesses a wood burning organic carbon contribution of about 60%. Finally, examples of functional group mass spectra of all

  14. Insights Into Water-Soluble Organic Aerosol Sources From Carbon-13 Ratios of Size Exclusion Chromatography Fractions

    NASA Astrophysics Data System (ADS)

    Ruehl, C. R.; Chuang, P. Y.; McCarthy, M. D.

    2008-12-01

    Many sources of organic aerosols have been identified and quantified, and much of this work has used individual (mosty water-insoluble) compounds as tracers of primary sources. However, most organic aerosol cannot be molecularly characterized, and the water-soluble organic carbon (WSOC) in many aerosols is thought to originate from gaseous precursors (i.e., it is secondary in nature). It can therefore be difficult to infer aerosol sources, particularly of background (i.e., aged) aerosols, and of the relatively high-MW component of aerosols. The stable isotope ratios (δ13C) of organic aerosols have been used to distinguish between sources, with lighter values (-30‰ to -25‰) interpreted as having originated from fossil fuel combustion and C4 biogenic emission, and heavier values (-25‰ to - 20‰) indicating a marine or C3 biogenic source. Most published measurements were of either total suspended particulates or PM2.5, however, and it is unknown to what extent these fractions differ from submicron WSOC. We report δ13C for submicron WSOC collected at a variety of sites, ranging from marine to polluted to background continental. Bulk marine organic δ13C ranged from -30.4 to - 27.6‰, slightly lighter than previously published results. This could be due to the elimination of supermicron cellular material or other biogenic primary emissions from the sample. Continental WSOC δ13C ranged from -19.1 to -29.8‰, with heavier values (-19.8 ± 1.0‰) in Oklahoma and lighter values at Great Smoky Mountain National Park in Tennessee (-25.8 ± 2.6‰) and Illinois (-24.5 ± 1.0‰). This likely results from the greater proportional of C3 plant material in the Oklahoma samples. In addition to bulk samples, we used size exclusion chromatography (SEC) to report δ13C of organic aerosols as a function of hydrodynamic diameter. Variability and magnitude of hydrodynamic diameter was greatest at low SEC pH, indicative of the acidic character of submicron WSOC. Tennessee

  15. Laboratory investigation of photochemical oxidation of organic aerosol from wood fires Part 2: Analysis of aerosol mass spectrometer data

    NASA Astrophysics Data System (ADS)

    Grieshop, A. P.; Donahue, N. M.; Robinson, A. L.

    2008-09-01

    Experiments were conducted to investigate the effects of photo-oxidation on organic aerosol (OA) in dilute wood smoke by exposing emissions from soft- and hard-wood fires to UV light in a smog chamber. This paper focuses on changes in OA composition measured using a unit mass resolution quadrupole Aerosol Mass Spectrometer (AMS). The results highlight how photochemical processing can lead to considerable evolution of the mass, the volatility and the level of oxygenation of biomass-burning OA. Photochemical oxidation produced substantial new OA, more than doubling the primary contribution after a few hours of aging under typical summertime conditions. Aging decreased the OA volatility of the total OA as measured with a thermodenuder; it also made the OA progressively more oxygenated in every experiment. With explicit knowledge of the condensed-phase mass spectrum (MS) of the primary emissions from each fire, each MS can be decomposed into primary and residual spectra throughout the experiment. The residual spectra provide an estimate of the composition of the photochemically produced OA. These spectra are also very similar to those of the oxygenated OA that dominates ambient AMS datasets. In addition, aged wood smoke spectra are shown to be similar to those from OA created by photo-oxidized dilute diesel exhaust and aged biomass-burning OA measured in urban and remote locations. This demonstrates that the oxygenated OA observed in the atmosphere can be produced by photochemical aging of dilute emissions from combustion of fuels containing both modern and fossil carbon.

  16. Water-soluble organic carbon (WSOC) and its temperature-resolved carbon fractions in atmospheric aerosols in Beijing

    NASA Astrophysics Data System (ADS)

    Tang, Xiong; Zhang, Xiaoshan; Wang, Zhangwei; Ci, Zhijia

    2016-11-01

    Investigation of temperature-resolved carbon fractions of water-soluble organic carbon (WSOC) can improve our understanding of the chemical properties, formation processes and sources of WSOC in aerosols. We developed a method that can examine different temperature-resolved carbon fractions of WSOC and used this method to characterize aerosol samples (n = 102) collected from an urban site in Beijing in 2010-2011. The aerosol composition data including inorganic ions, elements and temperature-resolved carbon fractions of WSOC were used as input of positive matrix factorization (PMF) model to investigate the sources of WSOC. The results showed that the mean concentrations of WSOC were 10.2 μg m- 3 with increased values in winter and decreased values in summer, while WSOC/OC ratios (mean: 51.7%) were higher in spring and summer than in fall and winter. The sampling artifacts of WSOC (18.2%) were higher than those of OC (13.4%). Though WSOC was significantly influenced by biomass burning in spring and winter, the strong correlations between WSOC and other secondary components suggested that WSOC was secondary in nature. Results of temperature-resolved carbon fractions of OC and WSOC showed that WSOC/OC ratios for different carbon fractions had the highest value of 0.92 and lowest value of 0.30. PMF analysis identified four factors, three of which were associated with three organic polar compounds groups (low, medium, and high molecular weight compounds) based on their thermal evolution features, and one of which was attributed to inorganic secondary formation processes. Annually, the contributions of four factors were 20.5%, 46.2%, 12.4% and 20.9%, respectively.

  17. Primary and secondary organic aerosols in urban air masses intercepted at a rural site

    NASA Astrophysics Data System (ADS)

    Liggio, John; Li, Shao-Meng; Vlasenko, Alexander; Sjostedt, Steve; Chang, Rachel; Shantz, Nicole; Abbatt, Jonathan; Slowik, J. G.; Bottenheim, J. W.; Brickell, P. C.; Stroud, C.; Leaitch, W. Richard

    2010-11-01

    Measurements made at a rural site in central Ontario during May-June 2007 are used to investigate the composition of organic aerosol (OA) downwind of an urban region. Observations of aerosol organic carbon and oxygen containing fragments from a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) are combined with toluene to benzene ratios to estimate the relative importance of secondary organic aerosol (SOA) and primary organic aerosol (POA) to the total OA at the site during periods of significant urban influence. We estimate that SOA formed within 1-2 days of the anthropogenic source regions was 40-50% of the measured OA and that POA was 5-16% of the OA. The remaining 35-45% of the OA is assumed to have been present in the aerosol upwind of the source regions prior to entering the study domain as defined by trajectories and estimates of the potential photochemical aging time. The apportionment results were also compared to that of positive matrix factorization analysis. In addition, the measurements of the molar oxygen to carbon ratio (O/C) in the OA demonstrates that SOA becomes progressively more oxygenated with increasing photochemical age and at low total OA mass.

  18. Mass distributions and morphological and chemical characterization of urban aerosols in the continental Balkan area (Belgrade).

    PubMed

    Đorđević, D; Buha, J; Stortini, A M; Mihajlidi-Zelić, A; Relić, D; Barbante, C; Gambaro, A

    2016-01-01

    This work presents characteristics of atmospheric aerosols of urban central Balkans area, using a size-segregated aerosol sampling method, calculation of mass distributions, SEM/EDX characterization, and ICP/MS analysis. Three types of mass distributions were observed: distribution with a pronounced domination of coarse mode, bimodal distribution, and distribution with minimum at 1 μm describing the urban aerosol. SEM/EDX analyses have shown morphological difference and variation in the content of elements in samples. EDX spectra demonstrate that particles generally contain the following elements: Al, Ca, K, Fe, Mg, Ni, K, Si, S. Additionally, the presence of As, Br, Sn, and Zn found in air masses from southeast segment points out the anthropogenic activities most probably from mining activities in southeastern part of Serbia. The ratio Al/Si equivalent to the ratio of desert dust was associated with air masses coming from southeastern and southwestern segments, pointing to influences from North Africa and Middle East desert areas whereas the Al/Si ratio in other samples is significantly lower. In several samples, we found high values of aluminum in the nucleation mode. Samples with low share of crustal elements in the coarse mode are collected when Mediterranean air masses prevailed, while high share in the coarse mode was associated with continental air masses that could be one of the approaches for identification of the aerosol origin. Graphical abstract ᅟ. PMID:26347417

  19. Characterization of Organic Nitrogen in the Atmosphere Using High Resolution Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Ge, X.; Sun, Y.; Chen, M.; Zhang, Q.

    2015-12-01

    Despite extensive efforts on characterizing organic nitrogen (ON) compounds in atmospheric aerosols and aqueous droplets, knowledge of ON chemistry is still limited, mainly due to its chemical complexity and lack of highly time-resolved measurements. This work is aimed at optimizing the method of using Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-AMS) to characterize ON compounds in atmospheric aerosols. Seventy-five pure nitrogen-containing organic compounds covering a variety of functional groups were analyzed with the HR-AMS. Our results show that ON compounds commonly produce NHx+, NOx+, which are usually attributed to inorganic N species such as ammonium and nitrate, and CH2N+ at m/z = 28, which is rarely quantified in ambient aerosol due to large interference from N2+ in the air signal. As a result, using the nitrogen-to-carbon (N/C) calibration factor proposed by Aiken et al. (2008) on average leads to ~ 20% underestimation of N/C in ambient organic aerosol. A new calibration factor of 0.79 is proposed for determining the average N/C in organics. The relative ionization efficiencies (RIEs) of different ON species, on average, are found to be consistent with the default RIE value (1.4) for the total organics. The AMS mass spectral features of various types of ON species (amines, amides, amino acids, etc.) are examined and used for characterizing ON composition in ambient aerosols. Our results indicate that submicron organic aerosol measured during wintertime in Fresno, CA contains significant amounts of amino-compounds whereas more diversified ON species, including N-containing aromatic heterocycle (e.g., imidazoles), are observed in fog waters collected simultaneously. Our findings have important implications for understanding atmospheric ON behaviors via the widespread HR-AMS measurements of ambient aerosols and droplets.

  20. Analysis of secondary organic aerosols from ozonolysis of isoprene by proton transfer reaction mass spectrometry

    NASA Astrophysics Data System (ADS)

    Inomata, Satoshi; Sato, Kei; Hirokawa, Jun; Sakamoto, Yosuke; Tanimoto, Hiroshi; Okumura, Motonori; Tohno, Susumu; Imamura, Takashi

    2014-11-01

    To understand the mechanism of formation of the secondary organic aerosols (SOAs) produced by the ozonolysis of isoprene, proton transfer reaction mass spectrometry (PTR-MS) was used to identify the semi-volatile organic compounds (SVOCs) produced in both the gaseous and the aerosol phases and to estimate the gas-aerosol partitioning of each SVOC in chamber experiments. To aid in the identification of the SVOCs, the products were also studied with negative ion-chemical ionization mass spectrometry (NI-CIMS), which can selectively detect carboxylic acids and hydroperoxides. The gaseous products were observed by on-line PTR-MS and NI-CIMS, whereas the SVOCs in SOAs collected on a filter were vaporized by heating the filter and were then analysed by off-line PTR-MS and NI-CIMS. The formation of oligomeric hydroperoxides involving a Criegee intermediate as a chain unit was observed in both the gaseous and the aerosol phases by NI-CIMS. PTR-MS also detected oligomeric hydroperoxides as protonated molecules from which a H2O molecule was eliminated, [M-OH]+. In the aerosol phase, oligomers involving formaldehyde and methacrolein as chain units were observed by PTR-MS in addition to oligomeric hydroperoxides. The gas-aerosol partitioning of each component was calculated from the ion signals in the gaseous and aerosol phases measured by PTR-MS. From the gas-aerosol partitioning, the saturated vapour pressures of the oligomeric hydroperoxides were estimated. Measurements by a fast-mobility-particle-sizer spectrometer revealed that the increase of the number density of the particles was complete within a few hundred seconds from the start of the reaction.

  1. Chemical Composition of the Aerosol Fine Fraction during African Dust Events as part of the Dust ATtACk Experiment in the Caribbean Region

    NASA Astrophysics Data System (ADS)

    Vallejo, Pamela; Formenti, Paola; Desboeufs, Karine; Quiñones, Mariana; Chevaillier, Servanne; Santos, Stephanie; Andrews, Elizabeth; Ogren, John A.; Mayol-Bracero, Olga L.

    2015-04-01

    We present results on the assessment of aerosols' chemical composition at the atmospheric observatory of Cabezas de San Juan in Fajardo, Puerto Rico, during the summers of 2011 and 2012, where periods in the presence and absence of dust were studied under the framework of the Dust-ATtACk (Dust- Aging and Transport, from Africa to the Caribbean) experiment. Dust events were identified through observation and using air-mass back-trajectories, Saharan Air Layer images, measurements of aerosol optical thickness (AOT), in situ scattering and absorption coefficients, and chemical analyses. Results obtained for intense dust events were characterized by higher concentration of coarse particles, higher scattering and absorption coefficients (up to 100 Mm-1 and 5 Mm-1 at 550 and 530 nm, respectively), higher AOT (from 0.4 to 0.8) values, and higher concentration of elements associated with mineral dust (e.g., Si μ3 g/m3 compared to background concentrations of 0.15 μg/m3, obtained from XRF analysis). Elemental composition of the fine fraction (Dp < 1.8 μm), analyzed by ICP-OES, also yielded higher average concentrations during dust events of, for example, Fe (0.045 μg m-3, vs 0.016 μg m-3 during low or no dust). Detailed results of the submicron fraction composition for the carbonaceous aerosol (total carbon, organic carbon, black carbon), total nitrogen, the water-soluble organic carbon, water-soluble ions, and the elemental composition with their possible sources will be presented at the meeting.

  2. Assessment of aerosol's mass concentrations from measured linear particle depolarization ratio (vertically resolved) and simulations

    NASA Astrophysics Data System (ADS)

    Nemuc, A.; Vasilescu, J.; Talianu, C.; Belegante, L.; Nicolae, D.

    2013-11-01

    Multi-wavelength depolarization Raman lidar measurements from Magurele, Romania are used in this study along with simulated mass-extinction efficiencies to calculate the mass concentration profiles of different atmospheric components, due to their different depolarization contribution to the 532 nm backscatter coefficient. Linear particle depolarization ratio (δpart) was computed using the relative amplification factor and the system-dependent molecular depolarization. The low depolarizing component was considered as urban/smoke, with a mean δpart of 3%, while for the high depolarizing component (mineral dust) a mean δpart of 35% was assumed. For this study 11 months of lidar measurements were analysed. Two study cases are presented in details: one for a typical Saharan dust aerosol intrusion, 10 June 2012 and one for 12 July 2012 when a lofted layer consisting of biomass burning smoke extended from 3 to 4.5 km height. Optical Properties of Aerosols and Clouds software package (OPAC) classification and conversion factors were used to calculate mass concentrations. We found that calibrated depolarization measurements are critical in distinguishing between smoke-reach aerosol during the winter and dust-reach aerosol during the summer, as well as between elevated aerosol layers having different origins. Good agreement was found between lidar retrievals and DREAM- Dust REgional Atmospheric Model forecasts in cases of Saharan dust. Our method was also compared against LIRIC (The Lidar/Radiometer Inversion Code) and very small differences were observed.

  3. Assessment of aerosol's mass concentrations from measured linear particle depolarization ratio (vertically resolved) and simulations

    NASA Astrophysics Data System (ADS)

    Nemuc, A.; Vasilescu, J.; Talianu, C.; Belegante, L.; Nicolae, D.

    2013-06-01

    Multiwavelength depolarization Raman lidar measurements from Magurele, Romania are used in this study along with simulated mass-extinction efficiencies to calculate the mass concentrations profiles of different atmospheric components, due to their different depolarization contribution to the 532 nm backscatter coefficient. Linear particle depolarization ratio (δpart) was computed using the relative amplification factor and the system-dependent molecular depolarization. The low depolarizing component was considered as urban/smoke, with a mean δpart of 3%, while for the high depolarizing component (mineral dust) a mean δpart of 35% was assumed. For this study 11 months of lidar measurements were analyzed. Two study cases are presented in details: one for a typical Saharan dust aerosol intrusion, 10 June 2012 and one for 12 July 2012 when a lofted layer consisting of biomass burning smoke extended from 3 to 4.5 km height. Optical Properties of Aerosols and Clouds software package (OPAC) classification and conversion factors were used to calculate mass concentrations. We found that calibrated depolarization measurements are critical to distinguish between smoke-reach aerosol during the winter and dust-reach aerosol during the summer, as well as between elevated aerosol layers having different origins. Good agreement was found between lidar retrievals and DREAM- Dust REgional Atmospheric Model forecasts in cases of Saharan dust. Our method was also compared against LIRIC (The Lidar/Radiometer Inversion Code) and very small differences were observed.

  4. Characterization of a real-time tracer for isoprene epoxydiols-derived secondary organic aerosol (IEPOX-SOA) from aerosol mass spectrometer measurements

    NASA Astrophysics Data System (ADS)

    Hu, W. W.; Campuzano-Jost, P.; Palm, B. B.; Day, D. A.; Ortega, A. M.; Hayes, P. L.; Krechmer, J. E.; Chen, Q.; Kuwata, M.; Liu, Y. J.; de Sá, S. S.; McKinney, K.; Martin, S. T.; Hu, M.; Budisulistiorini, S. H.; Riva, M.; Surratt, J. D.; St. Clair, J. M.; Isaacman-Van Wertz, G.; Yee, L. D.; Goldstein, A. H.; Carbone, S.; Brito, J.; Artaxo, P.; de Gouw, J. A.; Koss, A.; Wisthaler, A.; Mikoviny, T.; Karl, T.; Kaser, L.; Jud, W.; Hansel, A.; Docherty, K. S.; Alexander, M. L.; Robinson, N. H.; Coe, H.; Allan, J. D.; Canagaratna, M. R.; Paulot, F.; Jimenez, J. L.

    2015-10-01

    Substantial amounts of secondary organic aerosol (SOA) can be formed from isoprene epoxydiols (IEPOX), which are oxidation products of isoprene mainly under low-NO conditions. Total IEPOX-SOA, which may include SOA formed from other parallel isoprene oxidation pathways, was quantified by applying positive matrix factorization (PMF) to aerosol mass spectrometer (AMS) measurements. The IEPOX-SOA fractions of organic aerosol (OA) in multiple field studies across several continents are summarized here and show consistent patterns with the concentration of gas-phase IEPOX simulated by the GEOS-Chem chemical transport model. During the Southern Oxidant and Aerosol Study (SOAS), 78 % of PMF-resolved IEPOX-SOA is accounted by the measured IEPOX-SOA molecular tracers (2-methyltetrols, C5-Triols, and IEPOX-derived organosulfate and its dimers), making it the highest level of molecular identification of an ambient SOA component to our knowledge. An enhanced signal at C5H6O+ (m/z 82) is found in PMF-resolved IEPOX-SOA spectra. To investigate the suitability of this ion as a tracer for IEPOX-SOA, we examine fC5H6O (fC5H6O= C5H6O+/OA) across multiple field, chamber, and source data sets. A background of ~ 1.7 ± 0.1 ‰ (‰ = parts per thousand) is observed in studies strongly influenced by urban, biomass-burning, and other anthropogenic primary organic aerosol (POA). Higher background values of 3.1 ± 0.6 ‰ are found in studies strongly influenced by monoterpene emissions. The average laboratory monoterpene SOA value (5.5 ± 2.0 ‰) is 4 times lower than the average for IEPOX-SOA (22 ± 7 ‰), which leaves some room to separate both contributions to OA. Locations strongly influenced by isoprene emissions under low-NO levels had higher fC5H6O (~ 6.5 ± 2.2 ‰ on average) than other sites, consistent with the expected IEPOX-SOA formation in those studies. fC5H6O in IEPOX-SOA is always elevated (12-40 ‰) but varies substantially between locations, which is shown to reflect

  5. Characterization of a real-time tracer for isoprene epoxydiols-derived secondary organic aerosol (IEPOX-SOA) from aerosol mass spectrometer measurements

    DOE PAGESBeta

    Hu, W. W.; Campuzano-Jost, P.; Palm, B. B.; Day, D. A.; Ortega, A. M.; Hayes, P. L.; Krechmer, J. E.; Chen, Q.; Kuwata, M.; Liu, Y. J.; et al

    2015-10-23

    Substantial amounts of secondary organic aerosol (SOA) can be formed from isoprene epoxydiols (IEPOX), which are oxidation products of isoprene mainly under low-NO conditions. Total IEPOX-SOA, which may include SOA formed from other parallel isoprene oxidation pathways, was quantified by applying positive matrix factorization (PMF) to aerosol mass spectrometer (AMS) measurements. The IEPOX-SOA fractions of organic aerosol (OA) in multiple field studies across several continents are summarized here and show consistent patterns with the concentration of gas-phase IEPOX simulated by the GEOS-Chem chemical transport model. During the Southern Oxidant and Aerosol Study (SOAS), 78 % of PMF-resolved IEPOX-SOA is accountedmore » by the measured IEPOX-SOA molecular tracers (2-methyltetrols, C5-Triols, and IEPOX-derived organosulfate and its dimers), making it the highest level of molecular identification of an ambient SOA component to our knowledge. An enhanced signal at C5H6O+ (m/z 82) is found in PMF-resolved IEPOX-SOA spectra. To investigate the suitability of this ion as a tracer for IEPOX-SOA, we examine fC5H6O (fC5H6O= C5H6O+/OA) across multiple field, chamber, and source data sets. A background of ~ 1.7 ± 0.1 ‰ (‰ = parts per thousand) is observed in studies strongly influenced by urban, biomass-burning, and other anthropogenic primary organic aerosol (POA). Higher background values of 3.1 ± 0.6 ‰ are found in studies strongly influenced by monoterpene emissions. The average laboratory monoterpene SOA value (5.5 ± 2.0 ‰) is 4 times lower than the average for IEPOX-SOA (22 ± 7 ‰), which leaves some room to separate both contributions to OA. Locations strongly influenced by isoprene emissions under low-NO levels had higher fC5H6O (~ 6.5 ± 2.2 ‰ on average) than other sites, consistent with the expected IEPOX-SOA formation in those studies. fC5H6O in IEPOX-SOA is always elevated (12–40 ‰) but varies substantially between locations, which is shown

  6. Investigation of Aerosol Surface Area Estimation from Number and Mass Concentration Measurements: Particle Density Effect

    PubMed Central

    Ku, Bon Ki; Evans, Douglas E.

    2015-01-01

    For nanoparticles with nonspherical morphologies, e.g., open agglomerates or fibrous particles, it is expected that the actual density of agglomerates may be significantly different from the bulk material density. It is further expected that using the material density may upset the relationship between surface area and mass when a method for estimating aerosol surface area from number and mass concentrations (referred to as “Maynard’s estimation method”) is used. Therefore, it is necessary to quantitatively investigate how much the Maynard’s estimation method depends on particle morphology and density. In this study, aerosol surface area estimated from number and mass concentration measurements was evaluated and compared with values from two reference methods: a method proposed by Lall and Friedlander for agglomerates and a mobility based method for compact nonspherical particles using well-defined polydisperse aerosols with known particle densities. Polydisperse silver aerosol particles were generated by an aerosol generation facility. Generated aerosols had a range of morphologies, count median diameters (CMD) between 25 and 50 nm, and geometric standard deviations (GSD) between 1.5 and 1.8. The surface area estimates from number and mass concentration measurements correlated well with the two reference values when gravimetric mass was used. The aerosol surface area estimates from the Maynard’s estimation method were comparable to the reference method for all particle morphologies within the surface area ratios of 3.31 and 0.19 for assumed GSDs 1.5 and 1.8, respectively, when the bulk material density of silver was used. The difference between the Maynard’s estimation method and surface area measured by the reference method for fractal-like agglomerates decreased from 79% to 23% when the measured effective particle density was used, while the difference for nearly spherical particles decreased from 30% to 24%. The results indicate that the use of

  7. Evolution of organic aerosol mass spectra upon heating: implications for OA phase and partitioning behavior

    NASA Astrophysics Data System (ADS)

    Cappa, C. D.; Wilson, K. R.; Smith, J. D.; Kolesar, K.

    2010-12-01

    VUV mass spectra for two distinct aerosol types as they are passed through a thermodenuder at different temperatures have been measured. The two aerosol types considered are primary lubricating oil (LO) aerosol and secondary aerosol from the α-pinene + O3 reaction (αP). The evolution of the VUV mass spectra for the two aerosol types with temperature are observed to differ dramatically. For LO particles, the spectra exhibit distinct, T-dependent changes in which the lower m/z peaks, corresponding to compounds with higher vapor pressures, disappear more rapidly than the high m/z peaks. In stark contrast, the αP aerosol spectrum is essentially unchanged by temperature even though the particles experience significant mass loss due to evaporation. The variations in the LO spectra are found to be quantitatively in good agreement with expectations from absorptive partitioning theory whereas the αP spectra suggest that the evaporation of αP particles is not governed by partitioning theory. We postulate that this difference arises from the αP particles existing as a glass instead of having the expected liquid-like behavior. To reconcile these observations with decades of aerosol growth experiments, which indicate that OA formation is describable through equilibrium partitioning, we put forward a sequential partitioning model wherein secondary OA is rapidly converted from an absorbing form to a non-absorbing form. The results suggest that although OA growth may be describable through equilibrium partitioning theory, the thermodynamic properties of formed OA particles may differ significantly from the properties determined in the equilibrium framework.

  8. Size-fractionated water-soluble ions, situ pH and water content in aerosol on hazy days and the influences on visibility impairment in Jinan, China

    NASA Astrophysics Data System (ADS)

    Cheng, Shu-hui; Yang, Ling-xiao; Zhou, Xue-hua; Xue, Li-kun; Gao, Xiao-mei; Zhou, Yang; Wang, Wen-xing

    2011-09-01

    To study the size-fractionated characteristics of aerosol chemical compounds including major water-soluble inorganic and organic ions, situ pH and water content as well as their influences on visibility, field sample collections using a Micro Orifice Uniform Deposit Impactor (MOUDI) combined with simulations by Aerosol Inorganic Model (AIM) were conducted on hazy and clear days in Jinan, China from April, 2006 to January, 2007. Average concentrations of TSP, PM 10 and PM 1.8 on hazy days were found to be 1.49-5.13, 1.54-5.48 and 1.30-5.48 times those on clear days during the sampling periods, indicating that particulate pollution was very serious on hazy days. Size distributions of mass, SO 42-, NO 3-, formate and acetate were all bimodal with fine mode predominant on hazy days, demonstrating that fine particles and secondary pollutants were more easily formed on hazy days. The average total aerosol concentration of H + ([H +] total), of which free H + concentration ([H +] ins) inside aerosol accounted for 30%, was 2.36-4.21 times that in other cities in China and US. The [H +] ins on hazy days was 2.43-13.11 times that on clear days and the estimated situ pH was mainly influenced by RH and mole ratios of [NH 4+]/[SO 42-]. Size distributions of situ pH were unimodal peaked at 0.56 μm on clear days in spring and autumn as well as on hazy days in autumn, while a trend of increasing was shown on hazy days in spring and summer. The normalized water content (NWC) was higher on hazy days in autumn and winter because of the easier uptake of water by aerosol. It was found that when NWC < 2, if [NH 4+]/[SO 42-] < 2.0, aerosol chemical components were more sensitive to water content, while if [NH 4+]/[SO 42-] > 2.0, relative humidity (RH) was more important. Size distributions of water content showed a trend of sharp increasing on hazy days in spring and autumn. Correlation and regression analysis indicated that visibility was significantly influenced by the concentrations

  9. Laboratory investigation of photochemical oxidation of organic aerosol from wood fires 2: analysis of aerosol mass spectrometer data

    NASA Astrophysics Data System (ADS)

    Grieshop, A. P.; Donahue, N. M.; Robinson, A. L.

    2009-03-01

    Experiments were conducted to investigate the effects of photo-oxidation on organic aerosol (OA) in dilute wood smoke by exposing emissions from soft- and hard-wood fires to UV light in a smog chamber. This paper focuses on changes in OA composition measured using a unit-mass-resolution quadrupole Aerosol Mass Spectrometer (AMS). The results highlight how photochemical processing can lead to considerable evolution of the mass, volatility and level of oxygenation of biomass-burning OA. Photochemical oxidation produced substantial new OA, more than doubling the OA mass after a few hours of aging under typical summertime conditions. Aging also decreased the volatility of the OA and made it progressively more oxygenated. The results also illustrate strengths of, and challenges with, using AMS data for source apportionment analysis. For example, the mass spectra of fresh and aged BBOA are distinct from fresh motor-vehicle emissions. The mass spectra of the secondary OA produced from aging wood smoke are very similar to those of the oxygenated OA (OOA) that dominates ambient AMS datasets, further reinforcing the connection between OOA and OA formed from photo-chemistry. In addition, aged wood smoke spectra are similar to those from OA created by photo-oxidizing dilute diesel exhaust. This demonstrates that the OOA observed in the atmosphere can be produced by photochemical aging of dilute emissions from different types of combustion systems operating on fuels with modern or fossil carbon. Since OOA is frequently the dominant component of ambient OA, the similarity of spectra of aged emissions from different sources represents an important challenge for AMS-based source apportionment studies.

  10. MASS AND COMPOSITION OF AN URBAN AEROSOL AS A FUNCTION OF PARTICLE SIZE FOR SEVERAL VISIBILITY LEVELS

    EPA Science Inventory

    An atmospheric aerosol sampling analysis experiment at a site near the center of the New York metropolitan area was carried out to delineate relationships existing between degree of visibility and various aerosol characteristics in a polluted atmosphere. Size-fractionated and unf...

  11. Measuring the temporal evolution of aerosol composition in a remote marine environment influenced by Saharan dust outflow using a new single particle mass spectrometer.

    NASA Astrophysics Data System (ADS)

    Marsden, Nicholas; Williams, Paul; Flynn, Michael; Taylor, Jonathan; Liu, Dantong; Allan, James; Coe, Hugh

    2016-04-01

    Refractory material constitutes a significant fraction of the atmospheric aerosol burden and has a strong influence on climate through the direct radiative effect and aerosol-cloud interactions, particularly in cold and mixed phase clouds. Composition of refractory aerosols is traditionally measured using off-line analytical techniques such as filter analyses. However, when using off-line techniques the temporal evolution of the data set is lost, meaning the measurements are difficult to relate to atmospheric processes. Recently, single particle mass spectrometry (SPMS) has proven a useful tool for the on-line study of refractory aerosols with the ability to probe size resolved chemical composition with high temporal resolution on a particle by particle basis. A new Laser Ablation Aerosol Time-of-Flight (LAAP-TOF) SPMS instrument with a modified optical detection system was deployed for ground based measurements at Praia, Cape Verde during the Ice in Cloud - Dust (ICE-D) multi-platform campaign in August 2015. A primary aim of the project was to evaluate the impact of Saharan dust on ice nucleation in mixed phase clouds. The instrument was operated over a 16 day period in which several hundred thousand single particle mass spectra were obtained from air masses with back trajectories traversing the Mid-Atlantic, Sahara Desert and West Africa. The data presented indicate external mixtures of sea salt and silicate mineral dust internally mixed with secondary species that are consistent with long range transport to a remote marine environment. The composition and size distributions measured with the LAAP-TOF are compared with measurements from an aerodynamic particle sizer (APS), Single Particle Soot Photometer (SP2), and data from SEM-EDX analysis of filter samples. The particle number fraction identified as silicate mineral from the mass spectra correlates with a fraction of the incandescent particles measured with the SP2. We discuss the suitability of the modified

  12. Aerosol mass spectrometry: particle-vaporizer interactions and their consequences for the measurements

    NASA Astrophysics Data System (ADS)

    Drewnick, F.; Diesch, J.-M.; Faber, P.; Borrmann, S.

    2015-09-01

    The Aerodyne aerosol mass spectrometer (AMS) is a frequently used instrument for on-line measurement of the ambient sub-micron aerosol composition. With the help of calibrations and a number of assumptions on the flash vaporization and electron impact ionization processes, this instrument provides robust quantitative information on various non-refractory ambient aerosol components. However, when measuring close to certain anthropogenic or marine sources of semi-refractory aerosols, several of these assumptions may not be met and measurement results might easily be incorrectly interpreted if not carefully analyzed for unique ions, isotope patterns, and potential slow vaporization associated with semi-refractory species. Here we discuss various aspects of the interaction of aerosol particles with the AMS tungsten vaporizer and the consequences for the measurement results: semi-refractory components - i.e., components that vaporize but do not flash-vaporize at the vaporizer and ionizer temperatures, like metal halides (e.g., chlorides, bromides or iodides of Al, Ba, Cd, Cu, Fe, Hg, K, Na, Pb, Sr, Zn) - can be measured semi-quantitatively despite their relatively slow vaporization from the vaporizer. Even though non-refractory components (e.g., NH4NO3 or (NH4)2SO4) vaporize quickly, under certain conditions their differences in vaporization kinetics can result in undesired biases in ion collection efficiency in thresholded measurements. Chemical reactions with oxygen from the aerosol flow can have an influence on the mass spectra for certain components (e.g., organic species). Finally, chemical reactions of the aerosol with the vaporizer surface can result in additional signals in the mass spectra (e.g., WO2Cl2-related signals from particulate Cl) and in conditioning or contamination of the vaporizer, with potential memory effects influencing the mass spectra of subsequent measurements. Laboratory experiments that investigate these particle-vaporizer interactions are

  13. Mass spectrometric airborne measurements of submicron aerosol and cloud residual composition in tropic deep convection during ACRIDICON-CHUVA

    NASA Astrophysics Data System (ADS)

    Schulz, Christiane; Schneider, Johannes; Mertes, Stephan; Kästner, Udo; Weinzierl, Bernadett; Sauer, Daniel; Fütterer, Daniel; Walser, Adrian; Borrmann, Stephan

    2015-04-01

    Airborne measurements of submicron aerosol and cloud particles were conducted in the region of Manaus (Amazonas, Brazil) during the ACRIDICON-CHUVA campaign in September 2014. ACRIDICON-CHUVA aimed at the investigation of convective cloud systems in order to get a better understanding and quantification of aerosol-cloud-interactions and radiative effects of convective clouds. For that, data from airborne measurements within convective cloud systems are combined with satellite and ground-based data. We used a C-ToF-AMS (Compact-Time-of-Flight-Aerosol-Mass-Spectrometer) to obtain information on aerosol composition and vertical profiles of different aerosol species, like organics, sulphate, nitrate, ammonium and chloride. The instrument was operated behind two different inlets: The HASI (HALO Aerosol Submicrometer Inlet) samples aerosol particles, whereas the CVI (Counterflow Virtual Impactor) samples cloud droplets and ice particles during in-cloud measurements, such that cloud residual particles can be analyzed. Differences in aerosol composition inside and outside of clouds and cloud properties over forested or deforested region were investigated. Additionally, the in- and outflow of convective clouds was sampled on dedicated cloud missions in order to study the evolution of the clouds and the processing of aerosol particles. First results show high organic aerosol mass concentrations (typically 15 μg/m3 and during one flight up to 25 μg/m3). Although high amounts of organic aerosol in tropic air over rainforest regions were expected, such high mass concentrations were not anticipated. Next to that, high sulphate aerosol mass concentrations (about 4 μg/m3) were measured at low altitudes (up to 5 km). During some flights organic and nitrate aerosol was observed with higher mass concentrations at high altitudes (10-12 km) than at lower altitudes, indicating redistribution of boundary layer particles by convection. The cloud residuals measured during in

  14. Molecular composition of biogenic secondary organic aerosols using ultrahigh resolution mass spectrometry: linking laboratory and field studies

    NASA Astrophysics Data System (ADS)

    Kourtchev, Ivan; Fuller, Stephen; Aalto, Juho; Healy, Robert; Alfara, Rami; Ruuskanen, Taina; Wenger, John; McFiggans, Gordon; Kulmala, Markku; Kalberer, Markus

    2013-04-01

    Biogenic volatile organic compounds (BVOCs) play an important role in atmospheric chemistry and give rise to secondary organic aerosols (SOA), which have effects on climate and human health. Laboratory chamber experiments have been performed during several decades in an attempt to mimic atmospheric SOA formation. However, it is still unclear how close the aerosol particles generated in laboratory experiments resemble atmospheric SOA with respect to their detailed chemical composition. To date, most laboratory experiments have been performed using a single organic precursor (e.g., alpha- or beta-pinene, isoprene) while in the atmosphere a wide range of precursors contribute to SOA, which results most likely in a more complex SOA composition compared to the one-precursor laboratory systems. The objective of this work is to compare laboratory generated SOA from oxidation of BVOCs mixtures and remote ambient samples using ultrahigh-resolution mass spectrometry (UHR-MS) that allows detection of hundreds of individual SOA constituents. We examined aerosol samples from a boreal forest site, Hyytiälä, Finland and determined that a dominant fraction of the detected compounds are reaction products of a multi-component mixture of BVOCs. In the subsequent smog chamber experiments, SOA was generated from the ozonolysis and OH initiated reactions with BVOC mixtures containing species (alpha- and beta-pinene, delta-3-carene, and isoprene) that are most abundant in Hyytiälä's environment. The laboratory experiments were performed at conditions (e.g., RH, aerosol seed, and VOC ratios) that would resemble those at the boreal sampling site during the summer period. The elemental composition of the complex mixtures from laboratory generated SOA samples were compared with field samples using statistical data analysis methods.

  15. Online Aerosol Mass Spectrometry of Single Micrometer-Sized Particles Containing Poly(ethylene glycol)

    SciTech Connect

    Bogan, M J; Patton, E; Srivastava, A; Martin, S; Fergenson, D; Steele, P; Tobias, H; Gard, E; Frank, M

    2006-10-25

    Analysis of poly(ethylene glycol)(PEG)-containing particles by online single particle aerosol mass spectrometers equipped with laser desorption ionization (LDI) is reported. We demonstrate that PEG-containing particles are useful in the development of aerosol mass spectrometers because of their ease of preparation, low cost, and inherently recognizable mass spectra. Solutions containing millimolar quantities of PEGs were nebulized and, after drying, the resultant micrometer-sized PEG containing particles were sampled. LDI (266 nm) of particles containing NaCl and PEG molecules of average molecular weight <500 generated mass spectra reminiscent of mass spectra of PEG collected by other MS schemes including the characteristic distribution of positive ions (Na{sup +} adducts) separated by the 44 Da of the ethylene oxide units separating each degree of polymerization. PEGs of average molecular weight >500 were detected from particles that also contained t the tripeptide tyrosine-tyrosine-tyrosine or 2,5-dihydroxybenzoic acid, which were added to nebulized solutions to act as matrices to assist LDI using pulsed 266 nm and 355 nm lasers, respectively. Experiments were performed on two aerosol mass spectrometers, one reflectron and one linear, that each utilize two time-of-flight mass analyzers to detect positive and negative ions created from a single particle. PEG-containing particles are currently being employed in the optimization of our bioaerosol mass spectrometers for the application of measurements of complex biological samples, including human effluents, and we recommend that the same strategies will be of great utility to the development of any online aerosol LDI mass spectrometer platform.

  16. Determination of minimum mass and spatial location of initiator for detonation of propylene oxide aerosols

    NASA Astrophysics Data System (ADS)

    Apparao, A.; Saji, J.; Balaji, M.; Devangan, A. K.; Rao, C. R.

    2016-06-01

    The mishandling of liquid fuels during production, processing or transportation can lead to the formation of combustible two-phase mixtures. These mixtures, with the availability of a suitable energy source, may be ignited generating a deflagration, or even a detonation wave. For military applications, unconfined fuel aerosols are created and detonated with the help of a strong shock generated by a powerful energy source. The minimum energy requirement is expressed in terms of the shock strength, or mass of the high-explosive-based initiator. In this study, the detonability of unconfined aerosols of 4.3 kg propylene oxide was studied by positioning different quantities of cylindrical-shaped initiators of RDX/wax (95/5) at a fixed spatial location in the aerosol cloud, and the minimum mass of the initiator required for detonation initiation was determined. The effect of spatial location and the requirement of initiator mass, especially at farther locations where the fuel concentration is likely to be lower and closer to the lower explosive limit, was also investigated. The experimental findings help identify the detonable zone in unconfined propylene oxide aerosol clouds for different combinations of spatial location and mass of initiator.

  17. HUMIDITY EFFECTS ON THE MASS SPECTRA OF SINGLE AEROSOL PARTICLES. (R823980)

    EPA Science Inventory

    On-line laser desorption ionization mass spectrometry has developed into a widely used method for chemical characterization of individual aerosol particles. In the present study, the spectra of laboratory-generated particles were obtained as a function of relative humidity to elu...

  18. Mass concentration and mineralogical characteristics of aerosol particles collected at Dunhuang during ACE-Asia

    NASA Astrophysics Data System (ADS)

    Shen, Z. X.; Cao, J. J.; Li, X. X.; Okuda, T.; Wang, Y. Q.; Zhang, X. Y.

    2006-03-01

    Measurements were performed in spring 2001 and 2002 to determine the characteristics of soil dust in the Chinese desert region of Dunhuang, one of the ground sites of the Asia-Pacific Regional Aerosol Characterization Experiment (ACE-Asia). The mean mass concentrations of total suspended particle matter during the spring of 2001 and 2002 were 317 mu g m(-3) and 307 mu g m(-3) respectively. Eleven dust storm events were observed with a mean aerosol concentration of 1095 mu g m(-3), while the non-dusty days with calm or weak wind speed had a background aerosol loading of 196 mu g m(-3) on average in the springtime. The main minerals detected in the aerosol samples by X-ray diffraction were illite, kaolinite, chlorite, quartz, feldspar, calcite and dolomite. Gypsum, halite and amphibole were also detected in a few samples. The mineralogical data also show that Asian dust is characterized by a kaolinite to chlorite (K/C) ratio lower than 1 whereas Saharan dust exhibits a K/C ratio larger than 2. Air mass back- trajectory analysis show that three families of pathways are associated with the aerosol particle transport to Dunhuang, but these have similar K/C ratios, which further demonstrates that the mineralogical characteristics of Asian dust are different from African dust.

  19. Quantitative determination of carbonaceous particle mixing state in Paris using single particle mass spectrometer and aerosol mass spectrometer measurements

    NASA Astrophysics Data System (ADS)

    Healy, R. M.; Sciare, J.; Poulain, L.; Crippa, M.; Wiedensohler, A.; Prévôt, A. S. H.; Baltensperger, U.; Sarda-Estève, R.; McGuire, M. L.; Jeong, C.-H.; McGillicuddy, E.; O'Connor, I. P.; Sodeau, J. R.; Evans, G. J.; Wenger, J. C.

    2013-04-01

    Single particle mixing state information can be a powerful tool for assessing the relative impact of local and regional sources of ambient particulate matter in urban environments. However, quantitative mixing state data are challenging to obtain using single particle mass spectrometers. In this study, the quantitative chemical composition of carbonaceous single particles has been estimated using an aerosol time-of-flight mass spectrometer (ATOFMS) as part of the MEGAPOLI 2010 winter campaign in Paris, France. Relative peak areas of marker ions for elemental carbon (EC), organic aerosol (OA), ammonium, nitrate, sulphate and potassium were compared with concurrent measurements from an Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), a thermal/optical OCEC analyser and a particle into liquid sampler coupled with ion chromatography (PILS-IC). ATOFMS-derived mass concentrations reproduced the variability of these species well (R2 = 0.67-0.78), and ten discrete mixing states for carbonaceous particles were identified and quantified. Potassium content was used to identify particles associated with biomass combustion. The chemical mixing state of HR-ToF-AMS organic aerosol factors, resolved using positive matrix factorization, was also investigated through comparison with the ATOFMS dataset. The results indicate that hydrocarbon-like OA (HOA) detected in Paris is associated with two EC-rich mixing states which differ in their relative sulphate content, while fresh biomass burning OA (BBOA) is associated with two mixing states which differ significantly in their OA/EC ratios. Aged biomass burning OA (OOA2-BBOA) was found to be significantly internally mixed with nitrate, while secondary, oxidized OA (OOA) was associated with five particle mixing states, each exhibiting different relative secondary inorganic ion content. Externally mixed secondary organic aerosol was not observed. These findings demonstrate the heterogeneity of primary and

  20. Quantitative determination of carbonaceous particle mixing state in Paris using single-particle mass spectrometer and aerosol mass spectrometer measurements

    NASA Astrophysics Data System (ADS)

    Healy, R. M.; Sciare, J.; Poulain, L.; Crippa, M.; Wiedensohler, A.; Prévôt, A. S. H.; Baltensperger, U.; Sarda-Estève, R.; McGuire, M. L.; Jeong, C.-H.; McGillicuddy, E.; O'Connor, I. P.; Sodeau, J. R.; Evans, G. J.; Wenger, J. C.

    2013-09-01

    Single-particle mixing state information can be a powerful tool for assessing the relative impact of local and regional sources of ambient particulate matter in urban environments. However, quantitative mixing state data are challenging to obtain using single-particle mass spectrometers. In this study, the quantitative chemical composition of carbonaceous single particles has been determined using an aerosol time-of-flight mass spectrometer (ATOFMS) as part of the MEGAPOLI 2010 winter campaign in Paris, France. Relative peak areas of marker ions for elemental carbon (EC), organic aerosol (OA), ammonium, nitrate, sulfate and potassium were compared with concurrent measurements from an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), a thermal-optical OCEC analyser and a particle into liquid sampler coupled with ion chromatography (PILS-IC). ATOFMS-derived estimated mass concentrations reproduced the variability of these species well (R2 = 0.67-0.78), and 10 discrete mixing states for carbonaceous particles were identified and quantified. The chemical mixing state of HR-ToF-AMS organic aerosol factors, resolved using positive matrix factorisation, was also investigated through comparison with the ATOFMS dataset. The results indicate that hydrocarbon-like OA (HOA) detected in Paris is associated with two EC-rich mixing states which differ in their relative sulfate content, while fresh biomass burning OA (BBOA) is associated with two mixing states which differ significantly in their OA / EC ratios. Aged biomass burning OA (OOA2-BBOA) was found to be significantly internally mixed with nitrate, while secondary, oxidised OA (OOA) was associated with five particle mixing states, each exhibiting different relative secondary inorganic ion content. Externally mixed secondary organic aerosol was not observed. These findings demonstrate the range of primary and secondary organic aerosol mixing states in Paris. Examination of the temporal

  1. Mass-dependent and -independent fractionation of isotopes in Ni and Pb chelate complex formation reactions

    NASA Astrophysics Data System (ADS)

    Nomura, Masao; Kudo, Takashi; Adachi, Atsuhiko; Aida, Masao; Fujii, Yasuhiko

    2013-11-01

    Mass independent fractionation (MIF) has been a very interesting topic in the field of inorganic isotope chemistry, in particular, geo- and cosmo- chemistry. In the present work, we studied the isotope fractionation of Ni(II) and Pb(II) ions in complex formation with chelating reagent EDTA. To obtain clear results on the mass dependence of the isotope fractionation, we have conducted long-distance ion exchange chromatography of Ni(II) and Pb(II), using chelate complex reagent EDTA. The results apparently show that the isotope fractionation in Ni complex formation system is governed by the mass dependent rule. On the other hand the isotope fractionation in the Pb complex system is governed by the mass independent rule or the nuclear volume effect.

  2. Mass-dependent and -independent fractionation of isotopes in Ni and Pb chelate complex formation reactions

    SciTech Connect

    Nomura, Masao; Kudo, Takashi; Adachi, Atsuhiko; Aida, Masao; Fujii, Yasuhiko

    2013-11-13

    Mass independent fractionation (MIF) has been a very interesting topic in the field of inorganic isotope chemistry, in particular, geo- and cosmo- chemistry. In the present work, we studied the isotope fractionation of Ni(II) and Pb(II) ions in complex formation with chelating reagent EDTA. To obtain clear results on the mass dependence of the isotope fractionation, we have conducted long-distance ion exchange chromatography of Ni(II) and Pb(II), using chelate complex reagent EDTA. The results apparently show that the isotope fractionation in Ni complex formation system is governed by the mass dependent rule. On the other hand the isotope fractionation in the Pb complex system is governed by the mass independent rule or the nuclear volume effect.

  3. Detection of cw-related species in complex aerosol particles deposited on surfaces with an ion trap-based aerosol mass spectrometer

    SciTech Connect

    Harris, William A; Reilly, Pete; Whitten, William B

    2007-01-01

    A new type of aerosol mass spectrometer was developed by minimal modification of an existing commercial ion trap to analyze the semivolatile components of aerosols in real time. An aerodynamic lens-based inlet system created a well-collimated particle beam that impacted into the heated ionization volume of the commercial ion trap mass spectrometer. The semivolatile components of the aerosols were thermally vaporized and ionized by electron impact or chemical ionization in the source. The nascent ions were extracted and injected into the ion trap for mass analysis. The utility of this instrument was demonstrated by identifying semivolatile analytes in complex aerosols. This study is part of an ongoing effort to develop methods for identifying chemical species related to CW agent exposure. Our efforts focused on detection of CW-related species doped on omnipresent aerosols such as house dust particles vacuumed from various surfaces found in any office building. The doped aerosols were sampled directly into the inlet of our mass spectrometer from the vacuumed particle stream. The semivolatile analytes were deposited on house dust and identified by positive ion chemical ionization mass spectrometry up to 2.5 h after deposition. Our results suggest that the observed semivolatile species may have been chemisorbed on some of the particle surfaces in submonolayer concentrations and may remain hours after deposition. This research suggests that identification of trace CW agent-related species should be feasible by this technique.

  4. Size-Segregated Aerosol Composition and Mass Loading of Atmospheric Particles as Part of the Pacific Northwest 2001(PNW2001) Air Quality Study In Puget Sound

    NASA Astrophysics Data System (ADS)

    Disselkamp, R. S.; Barrie, L. A.; Shutthanadan, S.; Cliff, S.; Cahill, T.

    2001-12-01

    In mid-August, 2001, an aircraft-based air-quality study was performed in the Puget Sound, WA, area entitled PNW2001 (http://www.pnl.gov/pnw2001). The objectives of this field campaign were the following: 1. reveal information about the 3-dimensional distribution of ozone, its gaseous precursors and fine particulate matter during weather conditions favoring air pollution; 2. derive information about the accuracy of urban and biogenic emissions inventories that are used to drive the air quality forecast models; and 3. examine the accuracy of modeled ozone concentration with that observed. In support of these efforts, we collected time-averaged ( { ~}10 minute averages), size-segregated, aerosol composition and mass-loading information using ex post facto analysis techniques of synchrotron x-ray fluorescence (s-XRF), proton induced x-ray emissions(PIXE), proton elastic scattering (PESA), and scanning transmission ion microscopy (STIM). This is the first time these analysis techniques have been used together on samples collected from aircraft using an optimized 3-stage rotating drum impactor. In our presentation, we will discuss the aerosol components in three aerosol size fractions as identified by statistical analysis of multielemental data (including total mass, H, Na, Mg, Al, Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Pb) and relate variations in these components to physical aerosol properties, other gaseous trace constituents and to air mass origin.

  5. In situ submicron organic aerosol characterization at a boreal forest research station during HUMPPA-COPEC 2010 using soft and hard ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Vogel, A. L.; Äijälä, M.; Corrigan, A. L.; Junninen, H.; Ehn, M.; Petäjä, T.; Worsnop, D. R.; Kulmala, M.; Russell, L. M.; Williams, J.; Hoffmann, T.

    2013-11-01

    , contained organic compounds up to 800 Da (MWom≈450 g mol-1), showing that the average molecular weight can vary significantly. The high measurement frequency of both AMS and APCI-IT-MS enabled the partitioning of selected organic acids between gas and particle phase as a function of the total particulate mass to be quantified. Surprisingly high fractions of the higher molecular weight organic acids were observed to reside in the gas phase. These observations might be a consequence of large equilibration timescales for semi-solid boreal forest aerosol, as has been recently hypothesized by Shiraiwa and Seinfeld (2012).

  6. In-situ submicron organic aerosol characterization at a boreal forest research station during HUMPPA-COPEC 2010 using soft and hard ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Vogel, A. L.; Äijälä, M.; Corrigan, A. L.; Junninen, H.; Ehn, M.; Petäjä, T.; Worsnop, D. R.; Kulmala, M.; Russell, L. M.; Williams, J.; Hoffmann, T.

    2013-07-01

    , contained organic compounds up to 800 Da (MWom ≈ 450 g mol-1), showing that the average molecular weight can vary significantly. The high measurement frequency of both, AMS and APCI-IT-MS, enabled the partitioning of selected organic acids between gas- and particle-phase as a function of the total particulate mass to be quantified. Surprisingly high fractions of the higher molecular weight organic acids were observed to reside in the gas phase. These observations might be a consequence of large equilibration timescales for semi-solid boreal forest aerosol, as it has been recently hypothesised by Shiraiwa and Seinfeld (2012).

  7. Acoustic emission detection for mass fractions of materials based on wavelet packet technology.

    PubMed

    Wang, Xianghong; Xiang, Jianjun; Hu, Hongwei; Xie, Wei; Li, Xiongbing

    2015-07-01

    Materials are often damaged during the process of detecting mass fractions by traditional methods. Acoustic emission (AE) technology combined with wavelet packet analysis is used to evaluate the mass fractions of microcrystalline graphite/polyvinyl alcohol (PVA) composites in this study. Attenuation characteristics of AE signals across the composites with different mass fractions are investigated. The AE signals are decomposed by wavelet packet technology to obtain the relationships between the energy and amplitude attenuation coefficients of feature wavelet packets and mass fractions as well. Furthermore, the relationship is validated by a sample. The larger proportion of microcrystalline graphite will correspond to the higher attenuation of energy and amplitude. The attenuation characteristics of feature wavelet packets with the frequency range from 125 kHz to 171.85 kHz are more suitable for the detection of mass fractions than those of the original AE signals. The error of the mass fraction of microcrystalline graphite calculated by the feature wavelet packet (1.8%) is lower than that of the original signal (3.9%). Therefore, AE detection base on wavelet packet analysis is an ideal NDT method for evaluate mass fractions of composite materials. PMID:25737229

  8. Identification of haze-creating sources from fine particulate matter in Dhaka aerosol using carbon fractions.

    PubMed

    Begum, Bilkis A; Hopke, Philip K

    2013-09-01

    Fine particulate matter (PM2.5) samples were simultaneously collected on Teflon and quartz filters between February 2010 and February 2011 at an urban monitoring site (CAMS2) in Dhaka, Bangladesh. The samples were collected using AirMetrics MiniVol samplers. The samples on Teflon filters were analyzed for their elemental composition by PIXE and PESA. Particulate carbon on quartz filters was analyzed using the IMPROVE thermal optical reflectance (TOR) method that divides carbon into four organic carbons (OC), pyrolized organic carbon (OP), and three elemental carbon (EC) fractions. The data were analyzed by positive matrix factorization using the PMF2 program. Initially, only total OC and total EC were included in the analysis and five sources, including road dust, sea salt and Zn, soil dust, motor vehicles, and brick kilns, were obtained. In the second analysis, the eight carbon fractions (OC1, OC2, OC3, OC4, OP, EC1, EC2, EC3) were included in order to ascertain whether additional source information could be extracted from the data. In this case, it is possible to identify more sources than with only total OC and EC. The motor vehicle source was separated into gasoline and diesel emissions and a fugitive Pb source was identified. Brick kilns contribute 7.9 microg/m3 and 6.0 microg/m3 of OC and EC, respectively, to the fine particulate matter based on the two results. From the estimated mass extinction coefficients and the apportioned source contributions, soil dust, brick kiln, diesel, gasoline, and the Pb sources were found to contribute most strongly to visibility degradation, particularly in the winter. PMID:24151680

  9. Enhanced source identification of southeast aerosols using temperature-resolved carbon fractions and gas phase components

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Wang, Yuhang; Russell, Armistead; Edgerton, Eric S.

    Four gas components (CO, SO 2, HNO 3 and NO y) and PM 2.5 (particulate matter ⩽2.5 μm in aerodynamic diameter) composition data including eight individual carbon fractions collected at four sites in Georgia and Alabama were analyzed with the positive matrix factorization (PMF) method. Multiple linear regression (MLR) was applied to regress the total PM mass against the estimated source contributions. The regression coefficients were used to scale the factor profiles. Nine factors were resolved at two urban sites (Atlanta, GA (JST) and Birmingham, AL (BHM)) and one rural site (Centerville, AL (CTR)). Eight factors were resolved at the other rural site (Yorkville, GA (YRK)). Six factors we refer to as soil, coal combustion/other, diesel emission, secondary sulfate, secondary nitrate, and wood smoke are common among the four sites. Two industry-related factors are similar at the two sites in the same state, but differ between states. Contrary to previous results using only PM 2.5 data with non-speciated EC and OC data, diesel and gasoline emission factors were resolved at the two urban sites instead of only one single motor vehicle factor; diesel and gasoline factors were also resolved at the CTR site and a diesel factor was found at YRK instead of no motor vehicle factors at the two rural sites. The inclusion of gas components also improved the identification of the coal combustion/other factor among the four sites. This study shows that inclusion of gas phase data and temperature-resolved fractional carbon data can enhance the resolving power of source apportionment studies, especially for the factors we refer to as gas, diesel, and coal combustion/other.

  10. Aerosol Charge Model Consistent with Flight Data from the ECOMA/MASS Rocket Campaign

    NASA Astrophysics Data System (ADS)

    Knappmiller, S.; Robertson, S. H.; Rapp, M.; Gumbel, J.; Horanyi, M.; Sternovsky, Z.; Friedrich, M.; Baumgarten, G.; Latteck, R.

    2009-12-01

    In August of 2007 two sounding rockets were launched from the Andoya Rocket Range, Norway carrying the MASS instrument (Mesospheric Aerosol Sampling Spectrometer). The instrument detects charged aerosols in four different mass ranges on four pairs of biased collector plates, one set for positive particles and one set for negative particles. The first sounding rocket was launched into PMSE and NLC on 3 August. The solar zenith angle was 93 degrees and NLC were seen in the previous hour at 83 km by the ALOMAR RMR lidar. NLC were also detected at the same altitude by rocket-borne photometer measurements. The data from the MASS instrument shows a negatively charged population with radii >3 nm in the 83-89 km altitude range, which is collocated with PMSE detected by the ALWIN radar. Smaller particles, 1-2 nm in radius with both positive and negative polarity were detected between 86-88 km. Positively charged particles <1 nm in radius were detected at the same altitude. A charging model is developed to investigate the coexistence of positively and negatively charged aerosols in the NLC environment. Natanson’s rate equations are used for the attachment of free electrons and ions and the model includes charging by photo-electron emission and photo-detachment. Although the MASS flight occurred during night time conditions, the solar flux was still significant to affect the charge state of the aerosols. The calculations are done assuming three types of particles with different photo-electron charging properties: 1) Icy NLC particles, 2) Hematite particles of meteoric origin as condensation nuclei, and 3) Hematite particles coated with ice. The charge model results are consistent with the MASS rocket data, displaying both positively and negatively charged aerosols for small radii and only negatively charged particles for large radii.

  11. Oxidative potential of size-fractionated atmospheric aerosol in urban and rural sites across Europe.

    PubMed

    Shafer, Martin M; Hemming, Jocelyn D C; Antkiewicz, Dagmara S; Schauer, James J

    2016-07-18

    In this study we applied several assays, an in vitro rat alveolar macrophage model, a chemical ROS probe (DTT, dithiothreitol), and cytokine induction (TNFα) to examine relationships between PM-induced generation of reactive oxygen species (ROS) and PM composition, using a unique set of size-resolved PM samples obtained from urban and rural environments across Europe. From April-July 2012, we collected PM from roadside canyon, roadside motorway, and background urban sites in each of six European cities and from three rural sites spanning the continent. A Hi-Vol sampler was used to collect PM in three size classes (PM>7, PM7-3, PM3) and PM was characterized for total elements, and oxidative activity quantified in unfiltered and filtered PM extracts. We measured a remarkable uniformity in air concentrations of ROS and especially DTT activity across the continent. Only a 4-fold difference was documented for DTT across the urban sites and a similar variance was documented for ROS, implying that chemical drivers of oxidative activity are relatively similar between sites. The ROS and DTT specific activity was greater at urban background sites (and also rural sites) than at urban canyon locations. PM3 dominated the size distribution of both ROS activity (86% of total) and DTT activity (76% of total), reflecting both the large contribution of PM3 to total PM mass levels and importantly the higher specific oxidative activity of the PM3 in comparison with the larger particles. The soluble fraction of total activity was very high for DTT (94%) as well as for ROS (64%) in the PM3. However in the larger PM size fractions the contributions of the insoluble components became increasingly significant. The dominance of the insoluble PM drivers of activity was particularly evident in the TNFα data, where the insoluble contribution to cytokine production could be 100-fold greater than that from soluble components. ROS and DTT activity were strongly correlated in the PM3 (r = 0

  12. In-Flight Chemical Composition Observations of Aircraft Emissions using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Ziemba, L. D.; Martin, R.; Moore, R.; Shook, M.; Thornhill, K. L., II; Winstead, E.; Anderson, B. E.

    2015-12-01

    Commercial aircraft are an important source of aerosols to the upper troposphere. The microphysical and chemical properties of these emitted aerosols govern their ability to act as ice nuclei, both in near-field contrails and for cirrus formation downstream. During the ACCESS-II (Alternative Fuel Effects on Contrails and Cruise Emissions) campaign, NASA DC-8 CFM56-2-C1 engine emissions were sampled systematically at a range of cruise-relevant thrust levels and at several altitudes. Sampling was done aboard the NASA HU-25 Falcon aircraft, which was equipped with a suite of aerosol and gas-phase instruments focused on assessing the effects of burning different fuel mixtures on aerosol properties and their associated contrails. Here we present in-flight measurements of particle chemical composition made by a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS). The AMS was able to sufficiently resolve near-field (within 100m) aircraft emissions plumes. Low-sulfur HEFA (hydro-processed esters and fatty-acids) and JetA fuels yielded particles that contained 11 and 8% sulfate, respectively, compared to 30% sulfate contribution for traditional JetA fuel. Each of the fuels produced organic aerosol with similarly low oxygen content. Lubrication oils, which are not a combustion product but result from leaks in the engine, were likely a dominant fraction of the measured organic mass based on mass-spectral marker analysis. These results are compared to similar engine conditions from ground-based testing.

  13. 40 CFR Table 3 to Subpart Mmmm of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2012 CFR

    2012-07-01

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  14. 40 CFR Table 5 to Subpart Oooo of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Code of Federal Regulations, 2014 CFR

    2014-07-01

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  15. 40 CFR Table 3 to Subpart IIIi of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 13 2012-07-01 2012-07-01 false Default Organic HAP Mass Fraction for... of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass... manufacturer's formulation data Solvent/solvent blend CAS. No. Averageorganic HAP mass fraction Typical...

  16. 40 CFR Table 5 to Subpart Oooo of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Code of Federal Regulations, 2012 CFR

    2012-07-01

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  17. 40 CFR Table 4 to Subpart Mmmm of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 13 2012-07-01 2012-07-01 false Default Organic HAP Mass Fraction for... MMMM of Part 63—Default Organic HAP Mass Fraction for Petroleum Solvent Groups a You may use the mass... manufacturer's formulation data. Solvent type Average organic HAP mass fraction Typical organic HAP, percent...

  18. 40 CFR Table 4 to Subpart Oooo of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 13 2013-07-01 2012-07-01 true Default Organic HAP Mass Fraction for... OOOO of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass... manufacturer's formulation data. Solvent/solvent blend CAS. No. Averageorganic HAP mass fraction...

  19. 40 CFR Table 5 to Subpart Oooo of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 13 2013-07-01 2012-07-01 true Default Organic HAP Mass Fraction for... OOOO of Part 63—Default Organic HAP Mass Fraction for Petroleum Solvent Groups a You may use the mass... manufacturer's formulation data: Solvent type Averageorganic HAP mass fraction Typical organic HAP, percent...

  20. 40 CFR Table 4 to Subpart Oooo of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 13 2012-07-01 2012-07-01 false Default Organic HAP Mass Fraction for... OOOO of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass... manufacturer's formulation data. Solvent/solvent blend CAS. No. Averageorganic HAP mass fraction...

  1. 40 CFR Table 4 to Subpart Oooo of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 13 2014-07-01 2014-07-01 false Default Organic HAP Mass Fraction for... OOOO of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass... manufacturer's formulation data. Solvent/solvent blend CAS. No. Averageorganic HAP mass fraction...

  2. 40 CFR Table 4 to Subpart IIIi of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 13 2013-07-01 2012-07-01 true Default Organic HAP Mass Fraction for... of Part 63—Default Organic HAP Mass Fraction for Petroleum Solvent Groups a You may use the mass... manufacturer's formulation data Solvent type Averageorganic HAP mass fraction Typical organic HAP, percent...

  3. 40 CFR Table 3 to Subpart IIIi of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 13 2014-07-01 2014-07-01 false Default Organic HAP Mass Fraction for... of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass... manufacturer's formulation data Solvent/solvent blend CAS. No. Averageorganic HAP mass fraction Typical...

  4. 40 CFR Table 3 to Subpart IIIi of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 13 2013-07-01 2012-07-01 true Default Organic HAP Mass Fraction for... of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass... manufacturer's formulation data Solvent/solvent blend CAS. No. Averageorganic HAP mass fraction Typical...

  5. 40 CFR Table 3 to Subpart Mmmm of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 13 2013-07-01 2012-07-01 true Default Organic HAP Mass Fraction for... MMMM of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass... organic HAP mass fraction must be used for that solvent blend. Otherwise, use the organic HAP...

  6. 40 CFR Table 4 to Subpart IIIi of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Code of Federal Regulations, 2014 CFR

    2014-07-01

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  7. 40 CFR Table 4 to Subpart IIIi of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 13 2012-07-01 2012-07-01 false Default Organic HAP Mass Fraction for... of Part 63—Default Organic HAP Mass Fraction for Petroleum Solvent Groups a You may use the mass... manufacturer's formulation data Solvent type Averageorganic HAP mass fraction Typical organic HAP, percent...

  8. 40 CFR Table 3 to Subpart Mmmm of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 13 2014-07-01 2014-07-01 false Default Organic HAP Mass Fraction for... MMMM of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass... organic HAP mass fraction must be used for that solvent blend. Otherwise, use the organic HAP...

  9. 40 CFR Table 4 to Subpart Mmmm of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups a

    Code of Federal Regulations, 2013 CFR

    2013-07-01

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  10. 40 CFR Table 3 to Subpart Pppp of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Default Organic HAP Mass Fraction for... Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the... solvent blend matches both the name and CAS number for an entry, that entry's organic HAP mass...

  11. Composition and effects of inhalable size fractions of atmospheric aerosols in the polluted atmosphere: part I. PAHs, PCBs and OCPs and the matrix chemical composition.

    PubMed

    Landlová, Linda; Cupr, Pavel; Franců, Juraj; Klánová, Jana; Lammel, Gerhard

    2014-05-01

    Atmospheric particulate matter (PM) abundance, mass size distribution (MSD) and chemical composition are parameters relevant for human health effects. The MSD and phase state of semivolatile organic pollutants were determined at various polluted sites in addition to the PM composition and MSD. The distribution pattern of pollutants varied from side to side in correspondence to main particle sources and PM composition. Levels of particle-associated polycyclic aromatic hydrocarbons (PAHs) were 1-30 ng m(-3) (corresponding to 15-35 % of the total, i.e., gas and particulate phase concentrations), of polychlorinated biphenyls (PCBs) were 2-11 pg m(-3) (4-26 % of the total) and of DDT compounds were 2-12 pg m(-3) (4-23 % of the total). The PM associated amounts of other organochlorine pesticides were too low for quantification. The organics were preferentially found associated with particles <0.45 μm of aerodynamic equivalent diameter. The mass fractions associated with sub-micrometer particles (PM0.95) were 73-90 %, 34-71 % and 36-81 % for PAHs, PCBs and DDT compounds, respectively. The finest particles fraction had the highest aerosol surface concentration (6.3-29.7)×10(-6) cm(-1) (44-70 % of the surface concentration of all size fractions). The data set was used to test gas-particle partitioning models for semivolatile organics for the first time in terms of the organics' MSD and size-dependent PM composition. The results of this study prove that at the various sites particles with diverse size, matrix composition, amount of contaminants and toxicological effects occur. Legislative regulation based on gravimetric determination of PM mass can clearly be insufficient for assessment. PMID:24488522

  12. Single particles measured by a light scattering module coupled to a time-of-flight aerosol mass spectrometer onboard the NOAA P-3 aircraft during SENEX

    NASA Astrophysics Data System (ADS)

    Liao, J.; Middlebrook, A. M.; Welti, A.; Sueper, D.; Murphy, D. M.

    2014-12-01

    Single particles in the eastern US were characterized by a light scattering module coupled to a time-of-flight aerosol mass spectrometer (LS-ToF-AMS) onboard the NOAA P-3 aircraft during the Southeastern Nexus (SENEX) campaign. Single particle data were collected for 30 seconds every 5 minutes. Aerosols larger than 200-300 nm in vacuum aerodynamic diameter can be optically detected by the 405 nm crystal laser and trigger the saving of single particle mass spectra. The measured single particles are internally-mixed as expected. The single particles were classified as prompt, delayed, and null based on the chemical ion signal arrival time difference between prediction from the light scattering signal and measurement by mass spectrometer and the presence or absence of a mass spectrum. On average the number fraction of particles detected as prompt, delayed, and null (no spectrum) is about 30%, 10%, and 60%. The number fraction of these three particle types varied with aerosol size, chemical composition and the investigation region and will be discussed in detail. For example, the number fraction of prompt particles was significantly higher for the flight to the Pennsylvania natural gas shale region on July 6, 2013, which is probably related to the chemical composition (more acidic) and phase of the ambient particles. These particle types and detection efficiency are related to the bouncing effect on the vaporizer and may provide insight into the non-unit AMS collection efficiency. Moreover, most of the particles larger than 800 nm in vacuum aerodynamic diameter sized with the traditional AMS PToF mode are delayed particles and their mass spectral signals appear to be affected by this process.

  13. SAGE and SAM II measurements of global stratospheric aerosol optical depth and mass loading

    NASA Technical Reports Server (NTRS)

    Kent, G. S.; Mccormick, M. P.

    1984-01-01

    Several volcanic eruptions between November 1979 and April 1981 have injected material into the stratosphere. The SAGE and SAM II satellite systems have measured, with global coverage, the 1-micron extinction produced by this material, and examples of the data product are shown in the form of global maps of stratospheric optical depth and altitude-latitude plots of zonal mean extinction. These data, and that for the volcanically quiet period in early 1979, have been used to determine the changes in the total stratospheric mass loading. Estimates have also been made of the contribution to the total aerosol mass from each eruption. It has been found that between 1979 and mid-1981, the total stratospheric aerosol mass increased from a background level of approximately 570,000 metric tons to a peak of approximately 1,300,000 metric tons.

  14. Dust and Pollution Aerosol Air Mass Mapping from Satellite Multi-angle Imaging

    NASA Astrophysics Data System (ADS)

    Kahn, R. A.; Nelson, D. L.; Yau, K. S.; Martonchik, J.; Diner, D. J.; Gaitley, B. J.; Russell, P.; Livingston, J.; Redemann, J.; Quinn, P. R.; Clarke, A. R.; Howell, S.; McNaughton, C.; Reid, J.; Holben, B.; Wendisch, M.; Petzold, A.

    2006-12-01

    One objective of the NASA Earth Observing System's Multi-angle Imaging SpectroRadiometer (MISR) is to map aerosol air mass types, based on retrieved column-average particle microphysical properties. Early results demonstrated the ability to distinguish three-to-five bins over the 0.1 to 2.5 micron aerosol size range, about two-to-four groupings of single-scattering albedo, and to separate spherical from randomly oriented non- spherical particles, under good but not ideal viewing conditions. These results relied heavily on the MISR Research Aerosol Retrieval algorithm, which allows flexibility in choosing retrieval patch size and location, component aerosol properties and mixtures, and mixture acceptance criteria, compared to early versions of the MISR Standard algorithm, designed to routinely process the entire global data set. Early mid-visible column aerosol optical depth results were validated against surface-based sun photometer measurements. The corresponding particle property results appeared qualitatively promising, but formal validation requires quantitative constraints on component particle properties and mixtures in a range of natural settings, available mainly from the combination of height-resolved and total column data collected by surface and airborne instruments during field campaigns. This presentation will highlight the latest detailed, multi-platform case studies, as well as MISR regional mapping, of smoke, Saharan dust, and mixtures of pollution aerosol and desert dust collected during the INTEX, SAMUM, and UAE-2 campaigns, respectively. The broader implications of these results for global, and especially regional, aerosol climate and air quality studies will also be discussed. This work is performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

  15. Organic Mass to Organic Carbon ratio in Atmospheric Aerosols: Observations and Global Simulations

    NASA Astrophysics Data System (ADS)

    Tsigaridis, K.; Kanakidou, M.; Daskalakis, N.

    2012-12-01

    Organic compounds play an important role in atmospheric chemistry and affect Earth's climate through their impact on oxidants and aerosol formation (e.g. O3 and organic aerosols (OA)). Due to the complexity of the mixture of organics in the atmosphere, the organic-mass-to-organic-carbon ratio (OM/OC) is often used to characterize the organic component in atmospheric aerosols. This ratio varies dependant on the aerosol origin and the chemical processing in the atmosphere. Atmospheric observations have shown that as OA and its precursor gases age in the atmosphere, it leads to the formation of more oxidized (O:C atomic ratio 0.6 to 0.8), less volatile and less hydrophobic compounds (particle growth factor at 95% relative humidity of 0.16 to 0.20) that have more similar properties than fresh aerosols. While reported OM:OC ratios observed over USA range between 1.29 and 1.95, indicating significant contribution of local pollution sources to the OC in that region, high O/C ratio associated with a high OM/OC ratio of 2.2 has been also observed for the summertime East Mediterranean aged aerosol. In global models, the OM/OC ratio is either calculated for specific compounds or estimated for compound groups. In the present study, we review OM/OC observations and compare them with simulations from a variety of models that contributed to the AEROCOM exercise. We evaluate the chemical processing level of atmospheric aerosols simulated by the models. A total of 32 global chemistry transport models are considered in this study with variable complexity of the representation of OM/OC ratio in the OA. The analysis provides an integrated view of the OM/OC ratio in the global atmosphere and of the accuracy of its representation in the global models. Implications for atmospheric chemistry and climate simulations are discussed.

  16. High time-resolution chemical characterization of the water-soluble fraction of ambient aerosols with PILS-TOC-IC and AMS

    NASA Astrophysics Data System (ADS)

    Timonen, H.; Aurela, M.; Carbone, S.; Saarnio, K.; Saarikoski, S.; Mäkelä, T.; Kulmala, M.; Kerminen, V.-M.; Worsnop, D. R.; Hillamo, R.

    2010-08-01

    A particle-into-liquid sampler (PILS) was coupled with a total organic carbon analyzer (TOC) and two ion chromatographs (IC) to enable high time-resolution measurements of water-soluble ions and water-soluble organic carbon (WSOC) by a single sampling and analytical set-up. The new high time-resolution measurement system, the PILS-TOC-IC, was able to provide essential chemical and physical information about fast changes in composition, concentrations and likely sources of the water-soluble fraction of atmospheric aerosol. The concentrations of major water-soluble ions and WSOC were measured by the PILS-TOC-IC system from 25 April to 28 May 2009. The data of the PILS-TOC-IC setup was compared with the data from the High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) data measured from 25 April to 8 May 2009. The measured water-soluble particulate organic matter (WSPOM) concentration varied typically from 0.10 to 8.8 μg m-3 (on average 1.5 μg m-3). The WSPOM contributed on average 51% to particulate organic matter (POM) measured with the AMS. The correlation between the data of all the online measurement devices (AMS, PILS-TOC-IC, semicontinuous EC/OC carbon analyzer and TEOM) was excellent. For sulfate, nitrate and ammonium the correlations between the PILS-TOC-IC and AMS were 0.93, 0.96 and 0.96, respectively. The correlation between WSPOM and POM was also strong (r = 0.88). The identified sources of WSPOM were long-range transported biomass burning and secondary organic aerosol (SOA) formation. WSPOM and oxalate produced in biomass burning were clearly correlated with carbon monoxide.

  17. Mixing state of particles with secondary species by single particle aerosol mass spectrometer in an atmospheric pollution event

    NASA Astrophysics Data System (ADS)

    Xu, Lingling; Chen, Jinsheng

    2016-04-01

    Single particle aerosol mass spectrometer (SPAMS) was used to characterize size distribution, chemical composition, and mixing state of particles in an atmospheric pollution event during 20 Oct. - 5 Nov., 2015 in Xiamen, Southeast China. A total of 533,012 particle mass spectra were obtained and clustered into six groups, comprising of industry metal (4.5%), dust particles (2.6%), carbonaceous species (70.7%), K-Rich particles (20.7%), seasalt (0.6%) and other particles (0.9%). Carbonaceous species were further divided into EC (70.6%), OC (28.5%), and mixed ECOC (0.9%). There were 61.7%, 58.3%, 4.0%, and 14.6% of particles internally mixed with sulfate, nitrate, ammonium and C2H3O, respectively, indicating that these particles had undergone significant aging processing. Sulfate was preferentially mixed with carbonaceous particles, while nitrate tended to mix with metal-containing and dust particles. Compared to clear days, the fractions of EC-, metal- and dust particles remarkably increased, while the fraction of OC-containing particles decreased in pollution days. The mixing state of particles, excepted for OC-containing particles with secondary species was much stronger in pollution days than that in clear days, which revealed the significant influence of secondary particles in atmospheric pollution. The different activity of OC-containing particles might be related to their much smaller aerodynamic diameter. These results could improve our understanding of aerosol characteristics and could be helpful to further investigate the atmospheric process of particles.

  18. Evolution of size-segregated aerosol mass concentration during the Antarctic summer at Northern Foothills, Victoria Land

    NASA Astrophysics Data System (ADS)

    Illuminati, Silvia; Bau, Sébastien; Annibaldi, Anna; Mantini, Caterina; Libani, Giulia; Truzzi, Cristina; Scarponi, Giuseppe

    2016-01-01

    Within the framework of the Italian National Programm for Antarctic Research (PNRA), the first direct gravimetric measurements of size-segregated aerosol fractions were carried out at Faraglione Camp, ˜3-km far from the Italian station "M. Zucchelli" (Terra Nova Bay, Ross Sea), during the 2014-2015 austral summer. A six-stage high-volume cascade impactor with size classes between 10 μm and 0.49 μm, and, in parallel, for comparison purposes, a PM10 high-volume sampler (50% cut-off aerodynamic diameter of 10 μm) were used. A 10-day sampling strategy was adopted. Aerosol mass measurements were carried out before and after exposure by using a microbalance specifically designed for the filter weight and placed inside a glove bag in order to maintain stable temperature and humidity conditions during weighing sessions. Measured atmospheric concentrations (referred to the "actual air conditions" of mean temperature of 268 K and mean pressure of 975 hPa) of size-segregated aerosol fractions showed the following values, given as size range, means (interquartile range): Dp < 0.49 μm, 0.33 (0.26-0.34) μg m-3; 0.49-0.95 μm, 0.20 (0.19-0.24) μg m-3; 0.95-1.5 μm, 0.16 (0.13-0.21) μg m-3; 1.5-3.0 μm 0.075 (0.05-0.11) μg m-3; 3.0-7.2 μm 0.12 (0.02-0.19) μg m-3; 7.2-10 μm 0.06 (0.01-0.03) μg m-3. The average mass concentration of the total PM10 at Faraglione Camp for the entire sampling period was 0.92 (0.67-1.1) μg m-3. Although a great variability, the aerosol mass concentration showed a tri-modal distribution, with an accumulation mode (in the range 0.1-1.0 μm) and two coarse modes (CM1 in the range 1.0-3.0 μm, and CM2 in the range 3.0-10 μm). From 50% to 90% of the PM10 mass comes from particles of a size smaller than 1.0 μm. The two coarse modes represented from ˜5% to ˜35% of the PM10, showing opposite seasonal trends (CM1 decreased while CM2 increased). During summer, PM10 mass concentration increased to a maximum of ˜1.6 μg m-3 at mid-December, while

  19. Functional characterization of the water-soluble organic carbon of size-fractionated aerosol in the southern Mississippi Valley

    NASA Astrophysics Data System (ADS)

    Chalbot, M.-C. G.; Brown, J.; Chitranshi, P.; Gamboa da Costa, G.; Pollock, E. D.; Kavouras, I. G.

    2014-06-01

    The chemical content of water-soluble organic carbon (WSOC) as a function of particle size was characterized in Little Rock, Arkansas in winter and spring 2013. The objectives of this study were to (i) compare the functional characteristics of coarse, fine and ultrafine WSOC and (ii) reconcile the sources of WSOC for periods when carbonaceous aerosol was the most abundant particulate component. The WSOC accounted for 5% of particle mass for particles with dp > 0.96 μm and 10% of particle mass for particles with dp < 0.96 μm. Non-exchangeable aliphatic (H-C), unsaturated aliphatic (H-C-C=), oxygenated saturated aliphatic (H-C-O), acetalic (O-CH-O) and aromatic (Ar-H) protons were determined by proton nuclear magnetic resonance (1H-NMR). The total non-exchangeable organic hydrogen concentrations varied from 4.1 ± 0.1 nmol m-3 for particles with 1.5 < dp < 3.0 μm to 73.9 ± 12.3 nmol m-3 for particles with dp < 0.49 μm. The molar H / C ratios varied from 0.48 ± 0.05 to 0.92 ± 0.09, which were comparable to those observed for combustion-related organic aerosol. The R-H was the most abundant group, representing about 45% of measured total non-exchangeable organic hydrogen concentrations, followed by H-C-O (27%) and H-C-C= (26%). Levoglucosan, amines, ammonium and methanesulfonate were identified in NMR fingerprints of fine particles. Sucrose, fructose, glucose, formate and acetate were associated with coarse particles. These qualitative differences of 1H-NMR profiles for different particle sizes indicated the possible contribution of biological aerosols and a mixture of aliphatic and oxygenated compounds from biomass burning and traffic exhausts. The concurrent presence of ammonium and amines also suggested the presence of ammonium/aminium nitrate and sulfate secondary aerosol. The size-dependent origin of WSOC was further corroborated by the increasing δ13C abundance from -26.81 ± 0.18‰ for the smallest particles to -25.93 ± 0.31‰ for the largest

  20. Functional characterization of the water-soluble organic carbon of size fractionated aerosol in the Southern Mississippi Valley

    NASA Astrophysics Data System (ADS)

    Chalbot, M.-C. G.; Brown, J.; Chitranshi, P.; Gamboa da Costa, G.; Pollock, E. D.; Kavouras, I. G.

    2014-02-01

    The chemical content of the water soluble organic carbon (WSOC) as a function of particle size was characterized in Little Rock, Arkansas in winter and spring 2013. The objectives of this study were to: (i) compare the functional characteristics of coarse, fine and ultrafine WSOC and (ii) reconcile the sources of WSOC for the period when carbonaceous aerosol was the most abundant particulate component. The WSOC accounted for 5% of particle mass for particles with dp > 0.96 μm and 10% of particle mass for particles with dp < 0.96 μm. Non-exchangeable aliphatic (H-C), unsaturated aliphatic (H-C-C=), oxygenated saturated aliphatic (H-C-O), acetalic (O-CH-O) and aromatic (Ar-H) protons were determined by proton nuclear magnetic resonance. The total non-exchangeable organic hydrogen concentrations varied from 4.1 ± 0.1 nmol m-3 for particles with 0.96 < dp < 1.5 μm to 73.9 ± 12.3 nmol m-3 for particles with dp < 0.49 μm, resulting in molar H / C ratios of 0.48 ± 0.05 to 0.92 ± 0.09 observed in combustion-related organic aerosol. The R-H was the most abundant group representing about 45% of measured total non-exchangeable organic hydrogen concentration followed by H-C-O (27%) and H-C-C= (26%). Levoglucosan, amines, ammonium and methanosulfonate were tentatively identified in NMR fingerprints of fine particles. Sucrose, fructose, glucose, formate and acetate were associated with coarse particles. These qualitative differences of 1H-NMR profiles for different particle sizes indicated the possible contribution of biological aerosol and a mixture of aliphatic and oxygenated compounds from biomass burning and traffic exhausts. The concurrent presence of ammonium and amines also suggested the presence of ammonium/aminium nitrate and sulfate secondary aerosol. The size-dependent origin of WSOC was further corroborated by the increasing δ13C abundance from -26.81 ± 0.18‰ for the smallest particles to -25.93 ± 0.31‰ for the largest particles and the relative

  1. Quantification of Kras mutant fraction in the lung DNA of mice exposed to aerosolized particulate vanadium pentoxide by inhalation.

    PubMed

    Banda, Malathi; McKim, Karen L; Haber, Lynne T; MacGregor, Judith A; Gollapudi, B Bhaskar; Parsons, Barbara L

    2015-08-01

    This study investigated whether Kras mutation is an early event in the development of lung tumors induced by inhalation of particulate vanadium pentoxide (VP) aerosols. A National Toxicology Program tumor bioassay of inhaled particulate VP aerosols established that VP-induced alveolar/bronchiolar carcinomas of the B6C3F1 mouse lung carried Kras mutations at a higher frequency than observed in spontaneous mouse lung tumors. Therefore, this study sought to: (1) characterize any Kras mutational response with respect to VP exposure concentration, and (2) investigate the possibility that amplification of preexisting Kras mutation is an early event in VP-induced mouse lung tumorigenesis. Male Big Blue B6C3F1 mice (6 mice/group) were exposed to aerosolized particulate VP by inhalation, 6h/day, 5 days/week for 4 or 8 weeks, using VP exposure concentrations of 0, 0.1, and 1 mg/m(3). The levels of two different Kras codon 12 mutations [GGT → GAT (G12D) and GGT → GTT (G12V)] were measured in lung DNAs by Allele-specific Competitive Blocker PCR (ACB-PCR). For both exposure concentrations (0.1 and 1.0mg/m(3)) and both time points (4 and 8 weeks), the mutant fractions observed in VP-exposed mice were not significantly different from the concurrent controls. Given that 8 weeks of inhalation of a tumorigenic concentration of particulate aerosols of VP did not result in a significant change in levels of lung Kras mutation, the data do not support either a direct genotoxic effect of VP on Kras or early amplification of preexisting mutation as being involved in the genesis of VP-induced mouse lung tumors under the exposure conditions used. Rather, the data suggest that accumulation of Kras mutation occurs later with chronic VP exposure and is likely not an early event in VP-induced mouse lung carcinogenesis. PMID:26232258

  2. Comparison of two methods for obtaining quantitative mass concentrations from aerosol time-of-flight mass spectrometry measurements.

    PubMed

    Qin, Xueying; Bhave, Prakash V; Prather, Kimberly A

    2006-09-01

    Aerosol time-of-flight mass spectrometry (ATOFMS) measurements provide continuous information on the aerodynamic size and chemical composition of individual particles. In this work, we compare two approaches for converting unscaled ATOFMS measurements into quantitative particle mass concentrations using (1) reference mass concentrations from a co-located micro-orifice uniform deposit impactor (MOUDI) with an accurate estimate of instrument busy time and (2) reference number concentrations from a co-located aerodynamic particle sizer (APS). Aerodynamic-diameter-dependent scaling factors are used for both methods to account for particle transmission efficiencies through the ATOFMS inlet. Scaling with APS data retains the high-resolution characteristics of the ambient aerosol because the scaling functions are specific for each hourly time period and account for a maximum in the ATOFMS transmission efficiency curve for larger-sized particles. Scaled mass concentrations obtained from both methods are compared with co-located PM(2.5) measurements for evaluation purposes. When compared against mass concentrations from a beta attenuation monitor (BAM), the MOUDI-scaled ATOFMS mass concentrations show correlations of 0.79 at Fresno, and the APS-scaled results show correlations of 0.91 at Angiola. Applying composition-dependent density corrections leads to a slope of nearly 1 with 0 intercept between the APS-scaled absolute mass concentration values and BAM mass measurements. This paper provides details on the methodologies used to convert ATOFMS data into continuous, quantitative, and size-resolved mass concentrations that will ultimately be used to provide a quantitative estimate of the number and mass concentrations of particles from different sources. PMID:16944899

  3. Functional group composition of ambient and source organic aerosols determined by tandem mass spectrometry

    NASA Astrophysics Data System (ADS)

    Dron, J.; El Haddad, I.; Temime-Roussel, B.; Jaffrezo, J.-L.; Wortham, H.; Marchand, N.

    2010-08-01

    The functional group composition of various organic aerosols (OA) is investigated using a recently developed analytical approach based on atmospheric pressure chemical ionisation-tandem mass spectrometry (APCI-MS/MS). The determinations of three functional groups contents are performed quantitatively by neutral loss (carboxylic and carbonyl groups, R-COOH and R-CO-Ŕ respectively) and precursor ion (nitro groups, R-NO2) scanning modes of a tandem mass spectrometer. Major organic aerosol sources are studied: vehicular emission and wood combustion for primary aerosol sources; and a secondary organic aerosol (SOA) produced through photooxidation of o-xylene. The results reveal significant differences in the functional group contents of these source aerosols. The laboratory generated SOA is dominated by carbonyls while carboxylics are preponderate in the wood combustion particles. On the other hand, vehicular emissions are characterised by a strong nitro content. The total amount of the three functional groups accounts for 1.7% (vehicular) to 13.5% (o-xylene photooxidation) of the organic carbon. Diagnostic functional group ratios are then used to tentatively discriminate sources of particles collected in an urban background environment located in an Alpine valley (Chamonix, France) during a strong winter pollution event. The three functional groups under study account for a total functionalisation rate of 2.2 to 3.8% of the organic carbon in this ambient aerosol, which is also dominated by carboxylic moieties. In this particular case study of a deep alpine valley during winter, we show that the nitro- and carbonyl-to-carboxylic diagnostic ratios can be a useful tool to discriminate sources. In these conditions, the total OA concentrations are highly dominated by wood combustion OA. This result is confirmed by an organic markers source apportionment approach which assess a wood burning organic carbon contribution of about 60%. Finally, examples of functional group mass

  4. Aerosol mass spectrometry: particle-vaporizer interactions and their consequences for the measurements

    NASA Astrophysics Data System (ADS)

    Drewnick, F.; Diesch, J.-M.; Faber, P.; Borrmann, S.

    2015-04-01

    The Aerodyne Aerosol Mass Spectrometer (AMS) is a frequently used instrument for on-line measurement of the ambient sub-micron aerosol composition. With the help of calibrations and a number of assumptions on the flash vaporization and electron impact ionization processes this instrument provides robust quantitative information on various ambient aerosol components. However, when measuring close to certain anthropogenic sources or in marine environments, several of these assumptions may not be met and measurement results might easily be misinterpreted. Here we discuss various aspects of the interaction of aerosol particles with the AMS tungsten vaporizer and the consequences for the measurement results: semi-refractory components, i.e. components that vaporize but do not flash vaporize at the vaporizer and ionizer temperatures, like metal halides (e.g. chlorides, bromides or iodides of Al, Ba, Cd, Cu, Fe, Hg, K, Na, Pb, Sr, Zn) can be measured semi-quantitatively despite their relatively slow vaporization from the vaporizer. Even though non-refractory components (e.g. NH4NO3 or (NH4)2SO4) vaporize quickly, their differences in vaporization kinetics can result in undesired biases in ion collection efficiency in the measurements. Chemical reactions with water vapor and oxygen from the aerosol flow can have an influence on the mass spectra for certain components (e.g. NH4NO3, (NH4)2SO4, organic species). Finally, chemical reactions of the aerosol with the vaporizer surface can result in additional signals in the mass spectra (e.g. WO2C2-related signals from particulate Cl) and in conditioning or contamination of the vaporizer with potential memory effects influencing the mass spectra of subsequent measurements. Laboratory experiments that investigate these particle-vaporizer interactions are presented and are discussed together with field results showing that measurements of typical continental or urban aerosols are not significantly affected while laboratory

  5. Outdoor and indoor aerosol size, number, mass and compositional dynamics at an urban background site during warm season

    NASA Astrophysics Data System (ADS)

    Talbot, N.; Kubelova, L.; Makes, O.; Cusack, M.; Ondracek, J.; Vodička, P.; Schwarz, J.; Zdimal, V.

    2016-04-01

    This paper describes the use of a unique valve switching system that allowed for high temporal resolution indoor and outdoor data to be collected concurrently from online C-ToF-AMS, SMPS and OC/EC, and offline BLPI measurements. The results reveal near real-time dynamic aerosol behaviour along a migration path from an outdoor to indoor environment. An outdoor reduction in NR-PM1 mass concentration occurred daily from AM (06:00-12:00) to PM (12:00-18:00). SO4 (26%-37%) [AM/PM] increased proportionally during afternoons at the expense of NO3 (18%-7%). The influences of mixing height, temperature and solar radiation were considered against the mean mass concentration loss for each species. Losses were then calculated according to species via a basic input/output model. NO3 lost the most mass during afternoon periods, which we attribute to the accelerated dissociation of NH4NO3 through increasing temperature and decreasing relative humidity. Indoor/outdoor (I/O) ratios varied from 0.46 for <40 nm to 0.65 for >100 nm. These ratios were calculated using average SMPS PNC measurements over the full campaign and corroborated using a novel technique of calculating I/O penetration ratios through the indoor migration of particles during a new particle formation event. This ratio was then used to observe changes in indoor composition relative to those outdoors. Indoor sampling was carried out in an undisturbed room with no known sources. Indoor concentrations were found to be proportional to those outdoors, with organic matter [2.7 μg/m3] and SO4 [1.7 μg/m3] being the most prominent species. These results are indicative of fairly rapid aerosol penetration, a source-free indoor environment and small afternoon I/O temperature gradients. Fine fraction NO3 was observed indoors in both real-time AMS PM1 and off-line BLPI measurements. Greater mass concentration losses were observed from filter measurements, highlighting an important time dependency factor when investigating semi

  6. Molecular-level Analysis of Size Resolved Secondary Organic Aerosol (SOA) Samples from CALNEX Bakersfield Using High Resolution Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    O'Brien, R. E.; Laskin, A.; Laskin, J.; Weber, R.; Goldstein, A. H.

    2011-12-01

    This project focuses on analyzing the identities of molecules that comprise oligomers in size resolved aerosol fractions. Since oligomers are generally too large and polar to be measured by typical GC/MS analysis, soft ionization with high resolution mass spectrometry is used to extend the range of observable compounds. Samples collected with a microorifice uniform deposition impactor (MOUDI) during CALNEX Bakersfield in June 2010 have been analyzed with nanospray desorption electrospray ionization (nano-DESI) and an Orbitrap mass spectrometer. The nano-DESI is a soft ionization technique that allows molecular ions to be observed and the Orbitrap has sufficient resolution to determine the elemental composition of almost all species above the detection limit. A large fraction of SOA is made up of high molecular weight oligomers which are thought to form through acid catalyzed reactions of photo-chemically processed volatile organic compounds (VOC). The formation of oligomers must be influenced by the VOCs available, the amount of atmospheric sulfate and nitrate, and the magnitude of photo-chemical processing, among other potential influences. We present the elemental composition of chemical species in SOA in the 0.18 to 0.32 micron size range, providing the first multi-day data set for the study of these oligomers in atmospheric samples. Possible formation pathways and sources of observed compounds will be examined by comparison to other concurrent measurements at the site.

  7. Toward new techniques to measure heterogeneous oxidation of aerosol: Electrodynamic Balance-Mass Spectrometry (EDB-MS) and Aerosol X-ray Photoelectron Spectroscopy

    NASA Astrophysics Data System (ADS)

    Jacobs, M. I.; Heine, N.; Xu, B.; Davies, J. F.; Kirk, B. B.; Kostko, O.; Alayoglu, S.; Wilson, K. R.; Ahmed, M.

    2015-12-01

    The chemical composition and physical properties of aerosol can be changed via heterogeneous oxidation with the OH radical. However, the physical state of the aerosol influences the kinetics of this reaction; liquid particles with a high diffusion coefficient are expected to be well mixed and homogenously oxidized, while oxidation of solid, diffusion-limited aerosol is expected to occur primarily on the surface, creating steep chemical gradients within the particle. We are working to develop several new techniques to study the heterogeneous oxidation of different types of aerosol. We are developing a "modular" electrodynamic balance (EDB) that will enable us to study heterogeneous oxidation at aqueous interfaces using a mass-spectrometer (and potentially other detection techniques). Using a direct analysis in real time (DART) interface, preliminary droplet train measurements have demonstrated single-droplet mass spectrometry to be possible. With long reaction times in our EDB, we will be able to study heterogeneous oxidation of a wide variety of organic species in aqueous droplets. Additionally, we are working to use aerosol photoemission and velocity map imaging (VMI) to study the surface of aerosol particles as they undergo heterogeneous oxidation. With VMI, we're able to collect electrons with a 4π collection efficiency over conventional electron energy analyzers. Preliminary results looking at the ozonolysis of squalene using ultraviolet photoelectron spectroscopy (UPS) show that heterogeneous oxidation kinetic data can be extracted from photoelectron spectra. By moving to X-ray photoemission spectroscopy (XPS), we will determine elemental and chemical composition of the aerosol surface. Thus, aerosol XPS will provide information on the steep chemical gradients that form as diffusion-limited aerosol undergo heterogeneous oxidation.

  8. Characterization of solvent-extractable organics in urban aerosols based on mass spectrum analysis and hygroscopic growth measurement.

    PubMed

    Mihara, Toshiyuki; Mochida, Michihiro

    2011-11-01

    To characterize atmospheric particulate organics with respect to polarity, aerosol samples collected on filters in the urban area of Nagoya, Japan, in 2009 were extracted using water, methanol, and ethyl acetate. The extracts were atomized and analyzed using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and a hygroscopicity tandem differential mobility analyzer. The atmospheric concentrations of the extracted organics were determined using phthalic acid as a reference material. Comparison of the organic carbon concentrations measured using a carbon analyzer and the HR-ToF-AMS suggests that organics extracted with water (WSOM) and ethyl acetate (EASOM) or those extracted with methanol (MSOM) comprise the greater part of total organics. The oxygen-carbon ratios (O/C) of the extracted organics varied: 0.51-0.75 (WSOM), 0.37-0.48 (MSOM), and 0.27-0.33 (EASOM). In the ion-group analysis, WSOM, MSOM, and EASOM were clearly characterized by the different fractions of the CH and CO(2) groups. On the basis of the hygroscopic growth measurements of the extracts, κ of organics at 90% relative humidity (κ(org)) were estimated. Positive correlation of κ(org) with O/C (r 0.70) was found for MSOM and EASOM, but no clear correlation was found for WSOM. PMID:21877700

  9. Characterization of a real-time tracer for Isoprene Epoxydiols-derived Secondary Organic Aerosol (IEPOX-SOA) from aerosol mass spectrometer measurements

    NASA Astrophysics Data System (ADS)

    Hu, W. W.; Campuzano-Jost, P.; Palm, B. B.; Day, D. A.; Ortega, A. M.; Hayes, P. L.; Krechmer, J. E.; Chen, Q.; Kuwata, M.; Liu, Y. J.; de Sá, S. S.; Martin, S. T.; Hu, M.; Budisulistiorini, S. H.; Riva, M.; Surratt, J. D.; St. Clair, J. M.; Isaacman-Van Wertz, G.; Yee, L. D.; Goldstein, A. H.; Carbone, S.; Artaxo, P.; de Gouw, J. A.; Koss, A.; Wisthaler, A.; Mikoviny, T.; Karl, T.; Kaser, L.; Jud, W.; Hansel, A.; Docherty, K. S.; Robinson, N. H.; Coe, H.; Allan, J. D.; Canagaratna, M. R.; Paulot, F.; Jimenez, J. L.

    2015-04-01

    Substantial amounts of secondary organic aerosol (SOA) can be formed from isoprene epoxydiols (IEPOX), which are oxidation products of isoprene mainly under low-NO conditions. Total IEPOX-SOA, which may include SOA formed from other parallel isoprene low-NO oxidation pathways, was quantified by applying Positive Matrix Factorization (PMF) to aerosol mass spectrometer (AMS) measurements. The IEPOX-SOA fractions of OA in multiple field studies across several continents are summarized here and show consistent patterns with the concentration of gas-phase IEPOX simulated by the GEOS-Chem chemical transport model. During the SOAS study, 78% of IEPOX-SOA is accounted for the measured molecular tracers, making it the highest level of molecular identification of an ambient SOA component to our knowledge. Enhanced signal at C5H6O+ (m/z 82) is found in PMF-resolved IEPOX-SOA spectra. To investigate the suitability of this ion as a tracer for IEPOX-SOA, we examine fC5H6O ( fC5H6O = C5H6O+/OA) across multiple field, chamber and source datasets. A background of ~ 1.7 ± 0.1‰ is observed in studies strongly influenced by urban, biomass-burning and other anthropogenic primary organic aerosol (POA). Higher background values of 3.1 ± 0.8‰ are found in studies strongly influenced by monoterpene emissions. The average laboratory monoterpene SOA value (5.5 ± 2.0‰) is 4 times lower than the average for IEPOX-SOA (22 ± 7‰). Locations strongly influenced by isoprene emissions under low-NO levels had higher fC5H6O (~ 6.5 ± 2.2‰ on average) than other sites, consistent with the expected IEPOX-SOA formation in those studies. fC5H6O in IEPOX-SOA is always elevated (12-40‰) but varies substantially between locations, which is shown to reflect large variations in its detailed molecular composition. The low fC5H6O (< 3‰) observed in non IEPOX-derived isoprene-SOA indicates that this tracer ion is specifically enhanced from IEPOX-SOA, and is not a tracer for all SOA from

  10. Characterization of a real-time tracer for Isoprene Epoxydiols-derived Secondary Organic Aerosol (IEPOX-SOA) from aerosol mass spectrometer measurements

    DOE PAGESBeta

    Hu, W. W.; Campuzano-Jost, P.; Palm, B. B.; Day, D. A.; Ortega, A. M.; Hayes, P. L.; Krechmer, J. E.; Chen, Q.; Kuwata, M.; Liu, Y. J.; et al

    2015-04-16

    Substantial amounts of secondary organic aerosol (SOA) can be formed from isoprene epoxydiols (IEPOX), which are oxidation products of isoprene mainly under low-NO conditions. Total IEPOX-SOA, which may include SOA formed from other parallel isoprene low-NO oxidation pathways, was quantified by applying Positive Matrix Factorization (PMF) to aerosol mass spectrometer (AMS) measurements. The IEPOX-SOA fractions of OA in multiple field studies across several continents are summarized here and show consistent patterns with the concentration of gas-phase IEPOX simulated by the GEOS-Chem chemical transport model. During the SOAS study, 78% of IEPOX-SOA is accounted for the measured molecular tracers, making itmore » the highest level of molecular identification of an ambient SOA component to our knowledge. Enhanced signal at C5H6O+ (m/z 82) is found in PMF-resolved IEPOX-SOA spectra. To investigate the suitability of this ion as a tracer for IEPOX-SOA, we examine fC5H6O ( fC5H6O = C5H6O+/OA) across multiple field, chamber and source datasets. A background of ~ 1.7 ± 0.1‰ is observed in studies strongly influenced by urban, biomass-burning and other anthropogenic primary organic aerosol (POA). Higher background values of 3.1 ± 0.8‰ are found in studies strongly influenced by monoterpene emissions. The average laboratory monoterpene SOA value (5.5 ± 2.0‰) is 4 times lower than the average for IEPOX-SOA (22 ± 7‰). Locations strongly influenced by isoprene emissions under low-NO levels had higher fC5H6O (~ 6.5 ± 2.2‰ on average) than other sites, consistent with the expected IEPOX-SOA formation in those studies. fC5H6O in IEPOX-SOA is always elevated (12–40‰) but varies substantially between locations, which is shown to reflect large variations in its detailed molecular composition. The low fC5H6O (< 3‰) observed in non IEPOX-derived isoprene-SOA indicates that this tracer ion is specifically enhanced from IEPOX-SOA, and is not a tracer for all SOA

  11. Real-time measurement of sodium chloride in individual aerosol particles by mass spectrometry

    NASA Technical Reports Server (NTRS)

    Sinha, M. P.; Friedlander, S. K.

    1985-01-01

    The method of particle analysis by mass spectrometry has been applied to the quantitative measurement of sodium chloride in individual particles on a real-time basis. Particles of known masses are individually introduced, in the form of a beam, into a miniature Knudsen cell oven (1600 K). The oven is fabricated from rhenium metal sheet (0.018 mm thick) and is situated in the ion source of a quadrupole mass spectrometer. A particle once inside the oven is trapped and completely volatilized; this overcomes the problem of partial volatilization due to particles bouncing from the filament surface. Individual particles are thermally volatilized and ionized inside the rhenium oven, and produce discrete sodium ion pulses whose intensities are measured with the quadrupole mass spectrometer. An ion pulse width of several milliseconds (4-12 ms) is found for particles in the mass range 1.3 x 10 to the -13th to 5.4 x 10 to the -11th g. The sodium ion intensity is found to be proportional to the particle mass to the 0.86-power. The intensity distribution for monodisperse aerosol particles possesses a geometric standard deviation of 1.09, showing that the method can be used for the determination of the mass distribution function with good resolution in a polydisperse aerosol.

  12. First observation of a mass independent isotopic fractionation in a condensation reaction

    NASA Technical Reports Server (NTRS)

    Thiemens, M. H.; Nelson, R.; Dong, Q. W.; Nuth, Joseph A., III

    1994-01-01

    Thiemens and Heidenreich (1983) first demonstrated that a chemically produced mass independent isotopic fractionation process could produce an isotopic composition which is identical to that observed in Allende inclusions. This raised the possibility that the meteoritic components could be produced by chemical, rather than nuclear processes. In order to develop a mechanistic model of the early solar system, it is important that relevant reactions be studied, particularly, those which may occur in the earliest condensation reactions. The isotopic results for isotopic fractionations associated with condensation processes are reported. A large mass independent isotopic fractionation is observed in one of the experiments.

  13. 40 CFR Table 4 to Subpart Rrrr of... - Default Organic HAP Mass Fraction for Petroleum Solvent Groups 1

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 12 2011-07-01 2009-07-01 true Default Organic HAP Mass Fraction for... Metal Furniture Pt. 63, Subpt. RRRR, Table 4 Table 4 to Subpart RRRR of Part 63—Default Organic HAP Mass Fraction for Petroleum Solvent Groups 1 You May Use the Mass Fraction Values in the Following Fable...

  14. 40 CFR Table 3 to Subpart Rrrr of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 12 2011-07-01 2009-07-01 true Default Organic HAP Mass Fraction for... Metal Furniture Pt. 63, Subpt. RRRR, Table 3 Table 3 to Subpart RRRR of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table...

  15. 40 CFR Table 6 to Subpart Kkkk of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 12 2011-07-01 2009-07-01 true Default Organic HAP Mass Fraction for... Metal Cans Pt. 63, Subpt. KKKK, Table 6 Table 6 to Subpart KKKK of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table...

  16. 40 CFR Table 3 to Subpart Pppp of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 13 2012-07-01 2012-07-01 false Default Organic HAP Mass Fraction for... 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction.... If a solvent blend matches both the name and CAS number for an entry, that entry's organic HAP...

  17. 40 CFR Table 3 to Subpart Pppp of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 13 2013-07-01 2012-07-01 true Default Organic HAP Mass Fraction for... 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction.... If a solvent blend matches both the name and CAS number for an entry, that entry's organic HAP...

  18. 40 CFR Table 3 to Subpart Pppp of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 13 2014-07-01 2014-07-01 false Default Organic HAP Mass Fraction for... 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction.... If a solvent blend matches both the name and CAS number for an entry, that entry's organic HAP...

  19. 40 CFR Table 3 to Subpart Rrrr of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Default Organic HAP Mass Fraction for... Metal Furniture Pt. 63, Subpt. RRRR, Table 3 Table 3 to Subpart RRRR of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table...

  20. 40 CFR Table 3 to Subpart Mmmm of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Default Organic HAP Mass Fraction for... Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction.... If a solvent blend matches both the name and CAS number for an entry, that entry's organic HAP...

  1. 40 CFR Table 6 to Subpart Kkkk of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Default Organic HAP Mass Fraction for... Metal Cans Pt. 63, Subpt. KKKK, Table 6 Table 6 to Subpart KKKK of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table...

  2. Effect of variable power levels on the yield of total aerosol mass and formation of aldehydes in e-cigarette aerosols.

    PubMed

    Gillman, I G; Kistler, K A; Stewart, E W; Paolantonio, A R

    2016-03-01

    The study objective was to determine the effect of variable power applied to the atomizer of refillable tank based e-cigarette (EC) devices. Five different devices were evaluated, each at four power levels. Aerosol yield results are reported for each set of 25 EC puffs, as mass/puff, and normalized for the power applied to the coil, in mass/watt. The range of aerosol produced on a per puff basis ranged from 1.5 to 28 mg, and, normalized for power applied to the coil, ranged from 0.27 to 1.1 mg/watt. Aerosol samples were also analyzed for the production of formaldehyde, acetaldehyde, and acrolein, as DNPH derivatives, at each power level. When reported on mass basis, three of the devices showed an increase in total aldehyde yield with increasing power applied to the coil, while two of the devices showed the opposite trend. The mass of formaldehyde, acetaldehyde, and acrolein produced per gram of total aerosol produced ranged from 0.01 to 7.3 mg/g, 0.006 to 5.8 mg/g, and <0.003 to 0.78 mg/g, respectively. These results were used to estimate daily exposure to formaldehyde, acetaldehyde, and acrolein from EC aerosols from specific devices, and were compared to estimated exposure from consumption of cigarettes, to occupational and workplace limits, and to previously reported results from other researchers. PMID:26743740

  3. Mexico City Aerosol Analysis during MILAGRO using High Resolution Aerosol Mass Spectrometry at the Urban Supersite (T0). Part 1: Fine Particle Composition and Organic Source Apportionment

    SciTech Connect

    Aiken, Allison; Salcedo, D.; Cubison, Michael J.; Huffman, J.; DeCarlo, Peter; Ulbrich, Ingrid M.; Docherty, Kenneth S.; Sueper, D. T.; Kimmel, Joel; Worsnop, Douglas R.; Trimborn, Achim; Northway, Megan; Stone, Elizabeth A.; Schauer, James J.; Volkamer, Rainer M.; Fortner, Edward; de Foy, B.; Wang, Jian; Laskin, Alexander; Shutthanandan, V.; Zheng, Junsheng; Zhang, Renyi; Gaffney, Jeffrey S.; Marley, Nancy A.; Paredes-Miranda, Guadalupe L.; Arnott, W. P.; Molina, Luisa T.; Sosa, G.; Jimenez, Jose L.

    2009-09-11

    Submicron aerosol was analyzed during the MILAGRO field campaign in March 2006 at the T0 urban supersite in Mexico City with a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and complementary instrumentation. Mass concentrations, diurnal cycles, and size distributions of inorganic and organic species are similar to results from the CENICA supersite in April 2003 with organic aerosol (OA) comprising about half of the fine PM mass. Positive Matrix Factorization (PMF) analysis of the high resolution OA spectra identifies three major components: chemically-reduced urban primary emissions (hydrocarbon-like OA, HOA), oxygenated OA (OOA, mostly secondary OA or SOA), and biomass burning OA (BBOA) that correlates with levoglucosan and acetonitrile. BBOA includes several very large plumes from regional fires and likely also some refuse burning.

  4. The dense gas mass fraction of molecular clouds in the Milky Way

    SciTech Connect

    Battisti, Andrew J.; Heyer, Mark H. E-mail: heyer@astro.umass.edu

    2014-01-10

    The mass fraction of dense gas within giant molecular clouds (GMCs) of the Milky Way is investigated using {sup 13}CO data from the Five College Radio Astronomy Observatory Galactic Plane Surveys and the Bolocam Galactic Plane Survey (BGPS) of 1.1 mm dust continuum emission. A sample of 860 compact dust sources are selected from the BGPS catalog and kinematically linked to 344 clouds of extended (>3') {sup 13}CO J = 1-0 emission. Gas masses are tabulated for the full dust source and subregions within the dust sources with mass surface densities greater than 200 M {sub ☉} pc{sup –2}, which are assumed to be regions of enhanced volume density. Masses of the parent GMCs are calculated assuming optically thin {sup 13}CO J = 1-0 emission and local thermodynamic equilibrium conditions. The mean fractional mass of dust sources to host GMC mass is 0.11{sub −0.06}{sup +0.12}. The high column density subregions comprise 0.07{sub −0.05}{sup +0.13} of the mass of the cloud. Owing to our assumptions, these values are upper limits to the true mass fractions. The fractional mass of dense gas is independent of GMC mass and gas surface density. The low dense gas mass fraction suggests that the formation of dense structures within GMCs is the primary bottleneck for star formation. The distribution of velocity differences between the dense gas and the low density material along the line of sight is also examined. We find a strong, centrally peaked distribution centered on zero velocity displacement. This distribution of velocity differences is modeled with radially converging flows toward the dense gas position that are randomly oriented with respect to the observed line of sight. These models constrain the infall velocities to be 2-4 km s{sup –1} for various flow configurations.

  5. Coupled effects of temperature and mass transport on the isotope fractionation of zinc during electroplating

    NASA Astrophysics Data System (ADS)

    Black, Jay R.; John, Seth G.; Kavner, Abby

    2014-01-01

    The isotopic composition of zinc metal electrodeposited on a rotating disc electrode from a Zn-citrate aqueous solution was investigated as a function of overpotential (electrochemical driving force), temperature, and rotation rate. Zn metal was measured to be isotopically light with respect to Zn+2 in solution, with observed fractionations varying from Δ66/64Znmetal-aqueous = -1.0‰ to -3.9‰. Fractionation varies continuously as a function of a dimensionless parameter described by the ratio of observed deposition rate to calculated mass-transport limiting rate, where larger fractionations are observed at lower deposition rates, lower temperature, and at faster electrode rotation rates. Thus, the large fractionation and its rate dependence is interpreted as a competition between the two kinetic processes with different effective activation energies: mass-transport-limited (diffusion limited) kinetics with a large activation energy, which creates small fractionations close to the predicted diffusive fractionation; and electrochemical deposition kinetics, with a smaller effective activation energy, which creates large fractionations at low deposition rates and high hydrodynamic fluxes of solute to the electrode. The results provide a framework for predicting isotope fractionation in processes controlled by two competing reactions with different kinetic isotope effects. Light isotopes are electroplated. In all cases light stable isotopes of the metals are preferentially electroplated, with mass-dependent behavior evident where three or more isotopes are measured. Fractionation is time-independent, meaning that the fractionation factor does not vary with the extent of reaction. In most of our experiments, we have controlled the extent of reaction such that only a small amount of metal is deposited from the stock solution, thus avoiding significant evolution of the reservoir composition. In such experiments, the observed isotope fractionation is constant as a

  6. Response of an aerosol mass spectrometer to organonitrates and organosulfates and implications for atmospheric chemistry.

    PubMed

    Farmer, D K; Matsunaga, A; Docherty, K S; Surratt, J D; Seinfeld, J H; Ziemann, P J; Jimenez, J L

    2010-04-13

    Organonitrates (ON) are important products of gas-phase oxidation of volatile organic compounds in the troposphere; some models predict, and laboratory studies show, the formation of large, multifunctional ON with vapor pressures low enough to partition to the particle phase. Organosulfates (OS) have also been recently detected in secondary organic aerosol. Despite their potential importance, ON and OS remain a nearly unexplored aspect of atmospheric chemistry because few studies have quantified particulate ON or OS in ambient air. We report the response of a high-resolution time-of-flight aerosol mass spectrometer (AMS) to aerosol ON and OS standards and mixtures. We quantify the potentially substantial underestimation of organic aerosol O/C, commonly used as a metric for aging, and N/C. Most of the ON-nitrogen appears as NO(x)+ ions in the AMS, which are typically dominated by inorganic nitrate. Minor organonitrogen ions are observed although their identity and intensity vary between standards. We evaluate the potential for using NO(x)+ fragment ratios, organonitrogen ions, HNO(3)+ ions, the ammonium balance of the nominally inorganic ions, and comparison to ion-chromatography instruments to constrain the concentrations of ON for ambient datasets, and apply these techniques to a field study in Riverside, CA. OS manifests as separate organic and sulfate components in the AMS with minimal organosulfur fragments and little difference in fragmentation from inorganic sulfate. The low thermal stability of ON and OS likely causes similar detection difficulties for other aerosol mass spectrometers using vaporization and/or ionization techniques with similar or larger energy, which has likely led to an underappreciation of these species. PMID:20194777

  7. Thermal desorption single particle mass spectrometry of ambient aerosol in Shanghai

    NASA Astrophysics Data System (ADS)

    Zhai, Jinghao; Wang, Xinning; Li, Jingyan; Xu, Tingting; Chen, Hong; Yang, Xin; Chen, Jianmin

    2015-12-01

    Submicron aerosol volatility, chemical composition, and mixing state were simultaneously measured using a thermodenuder (TD) in-line with a single particle aerosol mass spectrometry (SPAMS) during Nov.12 to Dec. 11 of 2014 in Shanghai. By heating up to 250 °C, the signals of refractory species such as elemental carbon, metallic compounds, and mineral dust in aerosols were enhanced in the mass spectra. At 250 °C, the main particle types present in the size range of 0.2-1.0 μm were biomass burning (37% by number) and elemental carbon (20%). From 1.0 to 2.0 μm, biomass burning (30%), dust (19%) and metal-rich (18%) were the primary particle types. CN- signal remained in the mass spectra of the heated biomass burning particles suggests the existence of some extremely low-volatility nitrogen-containing organics. Laboratory experiments were conducted by burning rice straws, the main source material of biomass burning particles in Southern China, to confirm the less volatile composition contributed by biomass burning. Strong CN- with relative area >0.21 was observed in most of the laboratory-made biomass burning particles when heated above 200 °C and was selected as a new marker to identify the biomass burning particles in the field. The TD-SPAMS measured the size-resolved chemical composition of the individual particle residues at different temperatures and offered more information on the aging processes of primary particles and their sources.

  8. Aerosol formation from high-velocity uranium drops: Comparison of number and mass distributions. Final report

    SciTech Connect

    Rader, D.J.; Benson, D.A.

    1995-05-01

    This report presents the results of an experimental study of the aerosol produced by the combustion of high-velocity molten-uranium droplets produced by the simultaneous heating and electromagnetic launch of uranium wires. These tests are intended to simulate the reduction of high-velocity fragments into aerosol in high-explosive detonations or reactor accidents involving nuclear materials. As reported earlier, the resulting aerosol consists mainly of web-like chain agglomerates. A condensation nucleus counter was used to investigate the decay of the total particle concentration due to coagulation and losses. Number size distributions based on mobility equivalent diameter obtained soon after launch with a Differential Mobility Particle Sizer showed lognormal distributions with an initial count median diameter (CMD) of 0.3 {mu}m and a geometric standard deviation, {sigma}{sub g} of about 2; the CMD was found to increase and {sigma}{sub g} decrease with time due to coagulation. Mass size distributions based on aerodynamic diameter were obtained for the first time with a Microorifice Uniform Deposit Impactor, which showed lognormal distributions with mass median aerodynamic diameters of about 0.5 {mu}m and an aerodynamic geometric standard deviation of about 2. Approximate methods for converting between number and mass distributions and between mobility and aerodynamic equivalent diameters are presented.

  9. Analysis of charged aerosols in the mesosphere during the MASS/ECOMA rocket campaign

    NASA Astrophysics Data System (ADS)

    Knappmiller, Scott Robert

    In the polar summer mesosphere ice particles grow sufficiently large to scatter sunlight, giving rise to visible cloud displays called Noctilucent Clouds (NLC). In August of 2007, two sounding rockets were launched from the Andoya Rocket Range, Norway carrying the newly developed MASS instrument (Mesospheric Aerosol Sampling Spectrometer) to study NLC. The instrument detects charged aerosols in four different mass ranges on four pairs of biased collector plates, one set for positive particles and one set for negative particles. The first sounding rocket was launched into a Polar Mesospheric Summer echo (PMSE) and into a NLC on 3 August. The solar zenith angle was 93 degrees and NLC were seen in the previous hour at 83 km by the ALOMAR RMR lidar. NLC were also detected at the same altitude by rocket-borne photometer measurements. The data from the MASS instrument shows a negatively charged population with radii >3 nm in the 83--89 km altitude range, which is collocated with PMSE detected by the ALWIN radar. Smaller particles, 1--2 nm in radius with both positive and negative polarity were detected between 86--88 km. Positively charged particles <1 nm in radius were detected at the same altitude. This is the first time the charge number densities of positive and negative NLC particles have been measured simultaneously. A charging model is developed to investigate the coexistence of positively and negatively charged aerosols in the NLC environment as measured by the MASS instrument. Natanson's rate equations are used for the attachment of free electrons and ions and the model includes charging by photo-electron emission and photo-detachment. Although the MASS flight occurred during twilight conditions, the solar UV flux was still sufficient to affect the charge state of the aerosols. The calculations are done assuming three types of particles with different photo-electron charging properties: (1) Icy NLC particles, (2) Hematite particles of meteoric origin as

  10. Mass-Dependent and -Independent Fractionation of Hg Isotopes by Photoreduction in Aquatic Systems

    NASA Astrophysics Data System (ADS)

    Bergquist, Bridget A.; Blum, Joel D.

    2007-10-01

    Mercury (Hg) isotopes can be used as tracers of Hg biogeochemical pathways in the environment. The photochemical reduction of aqueous Hg species by natural sunlight leads to both mass-dependent fractionation (MDF) of Hg isotopes and mass-independent fractionation (MIF) of the odd-mass isotopes, with the relation between the MIF for the two odd isotopes being distinct for different photoreduction pathways. Large variations in MDF and MIF are observed in fish and provide new insights into the sources and bioaccumulation of Hg in food webs. MIF in fish can also be used to estimate the loss of methylmercury via photoreduction in aquatic ecosytems.

  11. Chemical composition and acidity of size-fractionated inorganic aerosols of 2013-14 winter haze in Shanghai and associated health risk of toxic elements

    NASA Astrophysics Data System (ADS)

    Behera, Sailesh N.; Cheng, Jinping; Huang, Xian; Zhu, Qiongyu; Liu, Ping; Balasubramanian, Rajasekhar

    2015-12-01

    The severe winter haze episode that occurred in Shanghai from December 2013 to January 2014, characterized by elevated levels of particulate matter (PM), received considerable international attention because of its impacts on public health and disruption of day-to-day activities. To examine the characteristics of PM during this haze episode and to assess the chemistry behind formation of secondary inorganic aerosols (SIA) and associated health impacts due to exposure of toxic elements, we characterized eight water soluble inorganic (WSI) ions and twenty four trace elements in twelve size-fractionated PM (10 nm-9.9 μm). The average mass concentrations of coarse (1.8 μm < Dp < 9.9 μm), fine (Dp < 2.5 μm), ultrafine (0.01 μm < Dp < 0.10 μm) and nano (0.01 μm < Dp < 0.056 μm) particles during hazy days were 2.8, 5.2, 5.3 and 5.1 times higher than those during non-hazy days, respectively. The in-situ pH (pHIS), as predicted by the Aerosol Inorganic Model (AIM-IV) in all sizes of PM, was observed to be lower during hazy days (average of -0.64) than that during non-hazy days (average of -0.29); there was an increased acidity in haze aerosols. Based on the measured concentrations of particulate-bound toxic elements, health risk assessment was conducted, which revealed that the excess lifetime carcinogenic risk to individuals exposed to fine particles under haze events increased significantly (P < 0.05) to 69 ± 18 × 10-6 compared to non-hazy days (34 ± 10 × 10-6). The qualitative source attribution analysis suggested that the occurrence of haze could be due to a combination of increased emissions of PM from multiple anthropogenic sources followed by its accumulation under unfavourable meteorological conditions with lower mixing heights and less wind speeds and the formation of secondary aerosols.

  12. Application of FIGAERO (Filter Inlet for Gases and AEROsol) coupled to a high resolution time of flight chemical ionization mass spectrometer to field and chamber organic aerosol: Implications for carboxylic acid formation and gas-particle partitioning from monoterpene oxidation

    NASA Astrophysics Data System (ADS)

    Lopez-Hilfiker, F.; Mohr, C.; Ehn, M.; Rubach, F.; Mentel, T. F.; Kleist, E.; Wildt, J.; Thornton, J. A.

    2013-12-01

    We present measurements of a large suite of gas and particle phase carboxylic acid containing compounds made with a Filter Inlet for Gas and AEROsol (FIGAERO) coupled to a high resolution time of flight chemical ionization mass spectrometer (HR-ToF-CIMS) developed at the University of Washington. A prototype operated with acetate negative ion proton transfer chemistry was deployed on the Julich Plant Atmosphere Chamber to study a-pinene oxidation, and a modified version was deployed at the SMEAR II forest station in Hyytiälä, Finland and SOAS, in Brent Alabama. We focus here on results from JPAC and Hyytiälä, where we utilized the same ionization method most selective towards carboxylic acids. In all locations, 100's of organic acid compounds were observed in the gas and particles and many of the same composition acids detected in the gas-phase were detected in the particles upon temperature programmed thermal desorption. Particulate organics detected by FIGAERO are highly correlated with organic aerosol mass measured by an AMS, providing additional volatility and molecular level information about collected aerosol. The fraction of a given compound measured in the particle phase follows expected trends with elemental composition, but many compounds would not be well described by an absorptive partitioning model assuming unity activity coefficients. Moreover the detailed structure in the thermal desorption signals reveals a contribution from thermal decomposition of large molecular weight organics and or oligomers with implications for partitioning measurements and model validation

  13. Mass Dependence of Iron Isotope Fractionation in Fe(II)-Fe(III) Electron Exchange Equilibration

    NASA Astrophysics Data System (ADS)

    Fujii, Yasuhiko; Kim, Sang-Ho; Nomura, Masao; Kawakami, Fumiaki

    2013-02-01

    A one hundred meter long ion-exchange chromatograph was used to establish rigorously the mass effects in the iron isotope fractionation in the Fe(II)-Fe(III) electron exchange equilibration.We used a highly porous, strongly basic anion exchange resin packed in glass columns. The abundance ratios of all natural iron isotopes, 54Fe, 56Fe, 57Fe, and 58Fe, in the effluent at the iron adsorption band boundary were measured with a mass spectrometer. The enrichment correlations among these isotopes were analyzed by three-isotope plots. The results clearly showed that the isotope fractionation of Fe(II)-Fe(III) is governed by the normal mass effect; the iron isotope fractionation is not proportional to the nuclear size, but proportional to the reduced mass difference of the pair of iron isotopes.

  14. Ambient particle characterization by single particle aerosol mass spectrometry in an urban area of Beijing

    NASA Astrophysics Data System (ADS)

    Li, Lei; Li, Mei; Huang, Zhengxu; Gao, Wei; Nian, Huiqing; Fu, Zhong; Gao, Jian; Chai, Fahe; Zhou, Zhen

    2014-09-01

    To investigate the composition and possible sources of aerosol particles in Beijing urban area, a single particle aerosol mass spectrometer (SPAMS) was deployed from April 22 to May 4, 2011. 510,341 particles out of 2,953,200 sized particles were characterized by SPAMS in combination with the ART-2a neural network algorithm. The particles were classified as rich-K (39.79%), carbonaceous species (32.7%), industry metal (19.2%), dust (5.7%), and rich-Na (1.76%). Industrial emissions related particles, rich-Fe, rich-Pb, and K-nitrate, were the major components of aerosol particles during haze periods, which were mainly from the steel plants and metal smelting processes around Beijing. Under stagnant meterological conditions, these regional emissions have a vital effect on haze formation. Organic carbon (OC) particles were attributed to biomass burning. NaK-EC was likely to come from local traffic emissions. Internally mixed organic and elemental carbon (OCEC) was found to be from possible sources of local traffic emission and biomass burning. It was found that coarse dust particles were mainly composed of four different types of dust particles, dust-Si, dust-Ca, dust-Al, and dust-Ti. It is the first time that SPAMS was used to study a dust storm in Beijing. Our results showed that SPAMS could be a powerful tool in the identification and apportionment of aerosol sources in Beijing, providing useful reference information for environmental control and management.

  15. Ultrasensitive detection of inhaled organic aerosol particles by accelerator mass spectrometry.

    PubMed

    Parkhomchuk, E V; Gulevich, D G; Taratayko, A I; Baklanov, A M; Selivanova, A V; Trubitsyna, T A; Voronova, I V; Kalinkin, P N; Okunev, A G; Rastigeev, S A; Reznikov, V A; Semeykina, V S; Sashkina, K A; Parkhomchuk, V V

    2016-09-01

    Accelerator mass spectrometry (AMS) was shown to be applicable for studying the penetration of organic aerosols, inhaled by laboratory mice at ultra-low concentration ca. 10(3) cm(-3). We synthesized polystyrene (PS) beads, composed of radiocarbon-labeled styrene, for testing them as model organic aerosols. As a source of radiocarbon we used methyl alcohol with radioactivity. Radiolabeled polystyrene beads were obtained by emulsifier-free emulsion polymerization of synthesized (14)C-styrene initiated by K2S2O8 in aqueous media. Aerosol particles were produced by pneumatic spraying of diluted (14)C-PS latex. Mice inhaled (14)C-PS aerosol consisting of the mix of 10(3) 225-nm particles per 1 cm(3) and 5·10(3) 25-nm particles per 1 cm(3) for 30 min every day during five days. Several millions of 225-nm particles deposited in the lungs and slowly excreted from them during two weeks of postexposure. Penetration of particles matter was also observed for liver, kidneys and brain, but not for a heart. PMID:27281540

  16. Monitoring aerosol elemental composition in particle size fractions of long-range transport

    NASA Astrophysics Data System (ADS)

    Metternich, P.; Georgii, H.-W.; Groeneveld, K. O.

    1983-04-01

    Collection of atmospheric samples was performed at Malta, a semi-remote environment in the Mediterranean, in case of long-range transport studies of pollutants and natural substances. Using PIXE as a non-destructive trace-element analytical tool, the elemental composition of these samples was determined. Atmospheric concentrations obtained in this study were of one magnitude higher than those observed over the open North Alantic in purely marine air. For most of the anomalously enriched elements in the Mediterranean aerosol, the high concentrations can be explained by long-range transport.

  17. High-Resolution Mass Spectrometry and Molecular Characterization of Aqueous Photochemistry Products of Common Types of Secondary Organic Aerosols

    SciTech Connect

    Romonosky, Dian E.; Laskin, Alexander; Laskin, Julia; Nizkorodov, Sergey

    2015-03-19

    A significant fraction of atmospheric organic compounds is predominantly found in condensed phases, such as aerosol particles and cloud droplets. Many of these compounds are photolabile and can degrade through direct photolysis or indirect photooxidation processes on time scales that are comparable to the typical lifetimes of aqueous droplets (hours) and particles (days). This paper presents a systematic investigation of the molecular level composition and the extent of aqueous photochemical processing in different types of secondary organic aerosol (SOA) from biogenic and anthropogenic precursors including α-pinene, β-pinene, β-myrcene, d- limonene, α-humulene, 1,3,5-trimethylbenzene, and guaiacol, oxidized by ozone (to simulate a remote atmosphere) or by OH in the presence of NOx (to simulate an urban atmosphere). Chamber- and flow tube-generated SOA samples were collected, extracted in a methanol/water solution, and photolyzed for 1 h under identical irradiation conditions. In these experiments, the irradiation was equivalent to about 3-8 h of exposure to the sun in its zenith. The molecular level composition of the dissolved SOA was probed before and after photolysis with direct-infusion electrospray ionization high-resolution mass spectrometry (ESI-HR-MS). The mass spectra of unphotolyzed SOA generated by ozone oxidation of monoterpenes showed qualitatively similar features, and contained largely overlapping subsets of identified compounds. The mass spectra of OH/NOx generated SOA had more unique visual appearance, and indicated a lower extent of products overlap. Furthermore, the fraction of nitrogen containing species (organonitrates and nitroaromatics) was highly sensitive to the SOA precursor. These observations suggest that attribution of high-resolution mass spectra in field SOA samples to specific SOA precursors should be more straightforward under OH/NOx oxidation conditions compared to the ozone driven oxidation. Comparison of the SOA constituents

  18. Aerosol Mass Spectrometry via Laser-Induced Incandescence Particle Vaporization Final Report

    SciTech Connect

    Timothy B. Onasch

    2011-10-20

    We have successfully developed and commercialized a soot particle aerosol mass spectrometer (SP-AMS) instrument to measure mass, size, and chemical information of soot particles in ambient environments. The SP-AMS instrument has been calibrated and extensively tested in the laboratory and during initial field studies. The first instrument paper describing the SP-AMS has been submitted for publication in a peer reviewed journal and there are several related papers covering initial field studies and laboratory studies that are in preparation. We have currently sold 5 SP-AMS instruments (either as complete systems or as SP modules to existing AMS instrument operators).

  19. Chemical characterization of high-molar-mass fractions in a Norway spruce knotwood ethanol extract.

    PubMed

    Smeds, Annika I; Eklund, Patrik C; Willför, Stefan M

    2016-10-01

    The low-molar-mass (LMM) fraction, only, i.e., the GC-eluting compounds, which are mainly lignans, has been characterized in Norway spruce knotwood hydrophilic extracts previously. Of this fraction, many lignans and sesquilignans and all GC peaks supposedly representing dilignans remain unidentified. In this work, dilignans and the GC non-eluting compounds (the high-molar mass fractions, HMM) were characterized in a 7-hydroxymatairesinol-reduced knotwood ethanol extract of Norway spruce by using several fractionation and analytical techniques. A methyl tert-butyl ether (MTBE) insoluble fraction of the extract contained mainly HMM material, of which the main part was shown to consist of lignan oligomers. The oligolignans (with a molar mass up to approximately 3700 Da) seemed to be linked by 55' bonds, some of them containing one or two guaiacylglycerol ether units linked to the lignan by βO4 or β5 bonds. Several oligolignans were identified or tentatively identified. The MTBE soluble fraction, which accounted for the major part (81%) of the extract, contained mainly LMM material (lignans, sesqui- and dilignans). The part of the HMM material in the MTBE soluble fraction that was easily isolable (2%) seemed to contain polymers of fatty acids and alcohols, resin acids, and sterols. PMID:27256310

  20. Chemical Nature Of Titan’s Organic Aerosols Constrained from Spectroscopic and Mass Spectrometric Observations

    NASA Astrophysics Data System (ADS)

    Imanaka, Hiroshi; Cruikshank, D. P.

    2012-10-01

    The Cassini-Huygens observations greately extend our knowledge about Titan’s organic aerosols. The Cassini INMS and CAPS observations clearly demonstrate the formation of large organic molecules in the ionosphere [1, 2]. The VIMS and CIRS instruments have revealed spectral features of the haze covering the mid-IR and far-IR wavelengths [3, 4, 5, 6]. This study attempts to speculate the possible chemical nature of Titan’s aerosols by comparing the currently available observations with our laboratory study. We have conducted a series of cold plasma experiment to investigate the mass spectrometric and spectroscopic properties of laboratory aerosol analogs [7, 8]. Titan tholins and C2H2 plasma polymer are generated with cold plasma irradiations of N2/CH4 and C2H2, respectively. Laser desorption mass spectrum of the C2H2 plasma polymer shows a reasonable match with the CAPS positive ion mass spectrum. Furthermore, spectroscopic features of the the C2H2 plasma polymer in mid-IR and far-IR wavelegths qualitatively show reasonable match with the VIMS and CIRS observations. These results support that the C2H2 plasma polymer is a good candidate material for Titan’s aerosol particles at the altitudes sampled by the observations. We acknowledge funding supports from the NASA Cassini Data Analysis Program, NNX10AF08G, and from the NASA Exobiology Program, NNX09AM95G, and the Cassini Project. [1] Waite et al. (2007) Science 316, 870-875. [2] Crary et al. (2009) Planet. Space Sci. 57, 1847-1856. [3] Bellucci et al. (2009) Icarus 201, 198-216. [4] Anderson and Samuelson (2011) Icarus 212, 762-778. [5] Vinatier et al. (2010) Icarus 210, 852-866. [6] Vinatier et al. (2012) Icarus 219, 5-12. [7] Imanaka et al. (2004) Icarus 168, 344-366. [8] Imanaka et al. (2012) Icarus 218, 247-261.

  1. Coupled effects of temperature and mass transport on the isotope fractionation of zinc during electroplating

    NASA Astrophysics Data System (ADS)

    Black, Jay R.; John, Seth G.; Kavner, Abby

    2014-01-01

    The isotopic composition of zinc metal electrodeposited on a rotating disc electrode from a Zn-citrate aqueous solution was investigated as a function of overpotential (electrochemical driving force), temperature, and rotation rate. Zn metal was measured to be isotopically light with respect to Zn+2 in solution, with observed fractionations varying from Δ66/64Znmetal-aqueous = -1.0‰ to -3.9‰. Fractionation varies continuously as a function of a dimensionless parameter described by the ratio of observed deposition rate to calculated mass-transport limiting rate, where larger fractionations are observed at lower deposition rates, lower temperature, and at faster electrode rotation rates. Thus, the large fractionation and its rate dependence is interpreted as a competition between the two kinetic processes with different effective activation energies: mass-transport-limited (diffusion limited) kinetics with a large activation energy, which creates small fractionations close to the predicted diffusive fractionation; and electrochemical deposition kinetics, with a smaller effective activation energy, which creates large fractionations at low deposition rates and high hydrodynamic fluxes of solute to the electrode. The results provide a framework for predicting isotope fractionation in processes controlled by two competing reactions with different kinetic isotope effects. Light isotopes are electroplated. In all cases light stable isotopes of the metals are preferentially electroplated, with mass-dependent behavior evident where three or more isotopes are measured. Fractionation is time-independent, meaning that the fractionation factor does not vary with the extent of reaction. In most of our experiments, we have controlled the extent of reaction such that only a small amount of metal is deposited from the stock solution, thus avoiding significant evolution of the reservoir composition. In such experiments, the observed isotope fractionation is constant as a

  2. A case for in vivo mass-independent fractionation of mercury isotopes in fish

    NASA Astrophysics Data System (ADS)

    Das, Reshmi; Salters, Vincent J. M.; Odom, A. Leroy

    2009-11-01

    The recent discovery of mass-independent fractionation of mercury isotopes allows new constraints to be placed on the mercury cycle. Here we report new Hg isotopic analyses of zooplankton and fish from different trophic levels of a freshwater lake (Lake Jackson, Florida) bearing systematic mass-independent fractionation of mercury isotopes. Fish muscle tissues show a progressive enrichment in the odd-mass mercury isotopes having odd atomic mass numbers (199 and 201) with increasing trophic level. Trophic level was determined based on nitrogen isotopic composition as well as fish stomach content. Zooplankton in the lake contain mercury with Δ199Hg and Δ201Hg values of +0.43 (±0.07)‰ and +0.44 (±0.07)‰, respectively. The Δ199Hg values increase by ˜1‰ from ˜+0.4‰ in zooplankton, juvenile bluegill, and several other small fishes to Δ199Hg = +1.36‰ for the Florida gar, which is the top predator fish in the lake. Previous observations of odd-mass-number isotope enrichment of mercury have been explained by photoreduction and demethylation of methyl mercury in the water column or as isotope effects related to microbial methylation. However, our data and the data of Jackson et al. (2008) are also consistent with in vivo production of mass-independent fractionation. Considering the alternatives, mass-independent fractionation by metabolic processes is the most straightforward explanation for the mercury isotope data. There are two known mechanisms for mass-independent fractionation of mercury, i.e., the nuclear volume effect and the magnetic isotope effect. While the data are insufficient to serve as proof, the magnitude of the mass-independent effect and the nearly equal enrichment of 199Hg and 201Hg seem most suggestive of a magnetic isotope effect.

  3. Mass-based hygroscopicity parameter interaction model and measurement of atmospheric aerosol water uptake

    NASA Astrophysics Data System (ADS)

    Mikhailov, E.; Vlasenko, S.; Rose, D.; Pöschl, U.

    2013-01-01

    In this study we derive and apply a mass-based hygroscopicity parameter interaction model for efficient description of concentration-dependent water uptake by atmospheric aerosol particles with complex chemical composition. The model approach builds on the single hygroscopicity parameter model of Petters and Kreidenweis (2007). We introduce an observable mass-based hygroscopicity parameter κm which can be deconvoluted into a dilute hygroscopicity parameter (κm0) and additional self- and cross-interaction parameters describing non-ideal solution behavior and concentration dependencies of single- and multi-component systems. For reference aerosol samples of sodium chloride and ammonium sulfate, the κm-interaction model (KIM) captures the experimentally observed concentration and humidity dependence of the hygroscopicity parameter and is in good agreement with an accurate reference model based on the Pitzer ion-interaction approach (Aerosol Inorganic Model, AIM). Experimental results for pure organic particles (malonic acid, levoglucosan) and for mixed organic-inorganic particles (malonic acid - ammonium sulfate) are also well reproduced by KIM, taking into account apparent or equilibrium solubilities for stepwise or gradual deliquescence and efflorescence transitions. The mixed organic-inorganic particles as well as atmospheric aerosol samples exhibit three distinctly different regimes of hygroscopicity: (I) a quasi-eutonic deliquescence & efflorescence regime at low-humidity where substances are just partly dissolved and exist also in a non-dissolved phase, (II) a gradual deliquescence & efflorescence regime at intermediate humidity where different solutes undergo gradual dissolution or solidification in the aqueous phase; and (III) a dilute regime at high humidity where the solutes are fully dissolved approaching their dilute hygroscopicity. For atmospheric aerosol samples collected from boreal rural air and from pristine tropical rainforest air (secondary

  4. Investigation of organic aerosol sources using fractionated water-soluble organic carbon measured at an urban site

    NASA Astrophysics Data System (ADS)

    Park, Seung Shik; Cho, Sung Yong; Kim, Kyung-Won; Lee, Kwon-Ho; Jung, Kweon

    2012-08-01

    Concentrations of carbonaceous aerosols in PM2.5, including elemental carbon (EC), organic carbon (OC), bulk water-soluble organic carbon (WSOC), fractionated WSOCs, and water-soluble inorganic species were measured between December 27, 2010 and January 20, 2011, at an urban site of Seoul, Korea. PM2.5 samples were collected twice a day, e.g., for the daytime (10:00-16:00) and nighttime (16:00-10:00), respectively. A macro-porous XAD7HP resin was used to separately group the liquid extracts into hydrophilic and hydrophobic WSOC (WSOCHPI and WSOCHPO). To better understand the contributions of primary and secondary OC (SOC) to WSOC, estimates of SOC were derived using the EC-tracer method and compared with the WSOC fractions. Good correlations among the WSOC, SO42-, and oxalate suggest that some of the observed WSOC originated from similar formation processes as those of SO42- and oxalate, i.e., formed by an in-cloud or aerosol droplet process. Primary OC was more highly correlated with the WSOCHPO (R2 = 0.56) than the WSOCHPI (R2 = 0.33), while a better correlation between predicted SOC and WSOCHPI (R2 = 0.63) was found than between the predicted SOC and WSOCHPO (R2 = 0.47). These results suggest that WSOCHPI at the site during the winter could be formed by a similar production pathway such as the secondary organic carbon, while primary combustion emissions were a dominant source for the WSOCHPO during the study period. Sources of WSOC, WSOCHPI and WSOCHPO inferred based on the correlations were also clearly demonstrated by source categories identified by principle component analysis. Measurement results suggest that group separation of bulk WSOC extracts could provide important clues for better understanding the sources of OC (or WSOC).

  5. Stable isotope ratio measurements of Cu and Zn in mineral dust (bulk and size fractions) from the Taklimakan Desert and the Sahel and in aerosols from the eastern tropical North Atlantic Ocean.

    PubMed

    Dong, Shuofei; Weiss, Dominik J; Strekopytov, Stanislav; Kreissig, Katharina; Sun, Youbin; Baker, Alex R; Formenti, Paola

    2013-09-30

    Accurate characterization of the stable isotope composition of Cu and Zn in major global mineral dust sources and in aerosols is central to the application of these isotope systems to the studies of global geochemical processes and cycles. We test here for the first time Cu and Zn isotope ratios within a well-defined source-receptor setting on the continent-ocean interface and determine the isotope composition of (i) bulk surface soil dust samples from the Sahel region, (ii) individual size fractions of surface dust samples from the Taklimakan Desert, and (iii) aerosols collected in the equatorial eastern North Atlantic region. This is achieved reducing the blank contribution during the ion exchange step using small resin and acid volumes and using a second ion exchange passage to purify the Cu fraction. We find no significant correlation between size fractions and isotope ratios in the two samples analyzed from the Taklimakan Desert. Mass balance calculations suggest that isotope ratios of bulk samples are within the analytical precision of the <4 μm size fraction and can be used to characterize atmospheric long range transport of Cu and Zn in mineral dust from the Taklimakan Desert. The <1 µm size fractions of two aerosol samples collected over the equatorial eastern North Atlantic region have Cu and Zn isotope ratios that are different to Sahel surface soil dust suggesting important non-crustal sources, in line with calculated enrichment factors, and possibly of anthropogenic origin. Using previously reported δ(66)Zn values for anthropogenic emission from Europe, preliminary calculations suggest that up to 55% of Zn arriving at the sampling points in the equatorial eastern North Atlantic region could be of anthropogenic origin. PMID:23953448

  6. Development of Soft Ionization for Particulate Organic Detection with the Aerodyne Aerosol Mass Spectrometer

    SciTech Connect

    Trimborn, A; Williams, L R; Jayne, J T; Worsnop, D R

    2008-06-19

    During this DOE SBIR Phase II project, we have successfully developed several soft ionization techniques, i.e., ionization schemes which involve less fragmentation of the ions, for use with the Aerodyne time-of-flight aerosol mass spectrometer (ToF-AMS). Vacuum ultraviolet single photon ionization was demonstrated in the laboratory and deployed in field campaigns. Vacuum ultraviolet single photon ionization allows better identification of organic species in aerosol particles as shown in laboratory experiments on single component particles, and in field measurements on complex multi-component particles. Dissociative electron attachment with lower energy electrons (less than 30 eV) was demonstrated in the measurement of particulate organics in chamber experiments in Switzerland, and is now a routine approach with AMS systems configured for bipolar, negative ion detection. This technique is particularly powerful for detection of acidic and other highly oxygenated secondary organic aerosol (SOA) chemical functionality. Low energy electron ionization (10 to 12 eV) is also a softer ionization approach routinely available to AMS users. Finally, Lithium ion attachment has been shown to be sensitive to more alkyl-like chemical functionality in SOA. Results from Mexico City are particularly exciting in observing changes in SOA molecular composition under different photochemical/meteorological conditions. More recent results detecting biomass burns at the Montana fire lab have demonstrated quantitative and selective detection of levoglucosan. These soft ionization techniques provide the ToF-AMS with better capability for identifying organic species in ambient atmospheric aerosol particles. This, in turn, will allow more detailed study of the sources, transformations and fate of organic-containing aerosol.

  7. Hollow-Fiber Flow Field-Flow Fractionation for Mass Spectrometry: From Proteins to Whole Bacteria

    NASA Astrophysics Data System (ADS)

    Reschiglian, Pierluigi; Zattoni, Andrea; Rambaldi, Diana Cristina; Roda, Aldo; Hee Moon, Myeong

    Mass spectrometry (MS) provides analyte identification over a wide molar-mass range. However, particularly in the case of complex matrices, this ability is often enhanced by the use of pre-MS separation steps. A separation, prototype technique for the "gentle" fractionation of large/ultralarge analytes, from proteins to whole cells, is here described to reduce complexity and maintain native characteristics of the sample before MS analysis. It is based on flow field-flow fractionation, and it employs a micro-volume fractionation channel made of a ca. 20 cm hollow-fiber membrane of sub-millimeter section. The key advantages of this technique lie in the low volume and low-cost of the channel, which makes it suitable to a disposable usage. Fractionation performance and instrumental simplicity make it an interesting methodology for in-batch or on-line pre-MS treatment of such samples.

  8. Single-particle aerosol mass spectrometry for the detection and identification of chemical warfare agent simulants.

    PubMed

    Martin, Audrey N; Farquar, George R; Frank, Matthias; Gard, Eric E; Fergenson, David P

    2007-08-15

    Single-particle aerosol mass spectrometry (SPAMS) was used for the real-time detection of liquid nerve agent simulants. A total of 1000 dual-polarity time-of-flight mass spectra were obtained for micrometer-sized single particles each of dimethyl methyl phosphonate, diethyl ethyl phosphonate, diethyl phosphoramidate, and diethyl phthalate using laser fluences between 0.58 and 7.83 nJ/microm2, and mass spectral variation with laser fluence was studied. The mass spectra obtained allowed identification of single particles of the chemical warfare agent (CWA) simulants at each laser fluence used although lower laser fluences allowed more facile identification. SPAMS is presented as a promising real-time detection system for the presence of CWAs. PMID:17630721

  9. Evolution of wavelength-dependent mass absorption cross sections of carbonaceous aerosols during the 2010 DOE CARES campaign

    NASA Astrophysics Data System (ADS)

    Flowers, B. A.; Dubey, M. K.; Subramanian, R.; Sedlacek, A. J.; Kelley, P.; Luke, W. T.; Jobson, B. T.; Zaveri, R. A.

    2011-12-01

    Predictions of aerosol radiative forcing require process level optical property models that are built on precise and accurate field observations. Evolution of aerosol optical properties for urban influenced carbonaceous aerosol undergoing transport and mixing with rural air masses was a focal point of the DOE Carbonaceous Aerosol and Radiative Effects (CARES) campaign near Sacramento, CA in summer 2010. Urban aerosol was transported from Sacramento, CA (T0) to the foothills of the Sierra Nevada Mountains to a rural site located near Cool, CA (T1). Aerosol absorption and scattering coefficients were measured at the T0 and T1 sites using integrated photoacoustic acoustic/nephelometer instruments (PASS-3 and PASS-UV) at 781, 532, 405, and 375 nm. Single particle soot photometry (SP2) instrumentation was used to monitor black carbon (BC) mass at both sites. Combining data from these sensors allows estimate of the wavelength-dependent mass absorption coefficient (MAC(λ)) and partitioning of MAC(λ) into contributions from the BC core and from enhancements from coating of BC cores. MAC(λ) measured in this way is free of artifacts associated with filter-based aerosol absorption measurements and takes advantage of the single particle sensitivity of the SP2 instrument, allowing observation of MAC(λ) on 10 minute and faster time scales. Coating was observed to enhance MAC(λ) by 20 - 30 % and different wavelength dependence for MAC(λ) was observed for urban and biomass burning aerosol. Further, T0 - T1 evolution of MAC(λ) was correlated with separately measured NO/NOy ratios and CO/CO2 ratios to understand the effects of aging & transport on MAC(λ) and the implications of aerosol processing that links air quality to radiative forcing on a regional scale. Aircraft observations made from the Gulfstream-1 during CARES are also analyzed to enhance process level understanding of the optical properties of fresh and aged carbonaceous aerosol in the urban-rural interface.

  10. Fractional iron solubility of aerosol particles enhanced by biomass burning and ship emission in Shanghai, East China.

    PubMed

    Fu, H B; Shang, G F; Lin, J; Hu, Y J; Hu, Q Q; Guo, L; Zhang, Y C; Chen, J M

    2014-05-15

    In terms of understanding Fe mobilization from aerosol particles in East China, the PM2.5 particles were collected in spring at Shanghai. Combined with the backtrajectory analysis, the PM2.5/PM10 and Ca/Al ratios, a serious dust-storm episode (DSE) during the sampling was identified. The single-particle analysis showed that the major iron-bearing class is the aluminosilicate dust during DSE, while the Fe-bearing aerosols are dominated by coal fly ash, followed by a minority of iron oxides during the non-dust storm days (NDS). Chemical analyses of samples showed that the fractional Fe solubility (%FeS) is much higher during NDS than that during DSE, and a strong inverse relationship of R(2)=0.967 between %FeS and total atmospheric iron loading were found, suggested that total Fe (FeT) is not controlling soluble Fe (FeS) during the sampling. Furthermore, no relationship between FeS and any of acidic species was established, suggesting that acidic process on aerosol surfaces are not involved in the trend of iron solubility. It was thus proposed that the source-dependent composition of aerosol particles is a primary determinant for %FeS. Specially, the Al/Fe ratio is poorly correlated (R(2)=0.113) with %FeS, while the apparent relationship between %FeS and the calculated KBB(+)/Fe ratio (R(2)=0.888) and the V/Fe ratio (R(2)=0.736) were observed, reflecting that %FeS could be controlled by both biomass burning and oil ash from ship emission, rather than mineral particles and coal fly ash, although the latter two are the main contributors to the atmospheric Fe loading during the sampling. Such information can be useful improving our understanding on iron solubility on East China, which may further correlate with iron bioavailability to the ocean, as well as human health effects associated with exposure to fine Fe-rich particles in densely populated metropolis in China. PMID:24607631

  11. Isotope mass fractionation during evaporation of Mg2SiO4

    NASA Technical Reports Server (NTRS)

    Davis, Andrew M.; Clayton, Robert N.; Mayeda, Toshiko K.; Hashimoto, Akihiko

    1990-01-01

    Synthetic forsterite (Mg2SiO4) was partially evaporated in vacuum for various durations and at different temperatures. The residual charges obtained when molten Mg2SiO4 was evaporated to 12 percent of its initial mass were enriched in heavy isotopes by about 20, 30, and 15 per mil/amu for O, Mg, and Si, respectively, whereas solid forsterite evaporated to a similar residual mass fraction showed negligible fractionations. These results imply that calcium and aluminum-rich refractory inclusions in carbonaceous chondrites must have been at least partially molten in the primordial solar nebula if the observed large mass fractionation effects were caused by evaporation processes in the nebula.

  12. Fire and biofuel contributions to annual mean aerosol mass concentrations in the United States

    NASA Astrophysics Data System (ADS)

    Park, Rokjin J.; Jacob, Daniel J.; Logan, Jennifer A.

    We estimate the contributions from biomass burning (summer wildfires, other fires, residential biofuel, and industrial biofuel) to seasonal and annual aerosol concentrations in the United States. Our approach is to use total carbonaceous (TC) and non-soil potassium (ns-K) aerosol mass concentrations for 2001-2004 from the nationwide IMPROVE network of surface sites, together with satellite fire data. We find that summer wildfires largely drive the observed interannual variability of TC aerosol concentrations in the United States. TC/ns-K mass enhancement ratios from fires range from 10 for grassland and shrub fires in the south to 130 for forest fires in the north. The resulting summer wildfire contributions to annual TC aerosol concentrations for 2001-2004 are 0.26 μg C m -3 in the west and 0.14 μg C m -3 in the east; Canadian fires are a major contributor in the east. Non-summer wildfires and prescribed burns contribute on an annual mean basis 0.27 and 0.31 μg C m -3 in the west and the east, highest in the southeast because of prescribed burning. Residential biofuel is a large contributor in the northeast with annual mean concentration of up to 2.2 μg C m -3 in Maine. Industrial biofuel (mainly paper and pulp mills) contributes up to 0.3 μg C m -3 in the southeast. Total annual mean fine aerosol concentrations from biomass burning average 1.2 and 1.6 μg m -3 in the west and east, respectively, contributing about 50% of observed annual mean TC concentrations in both regions and accounting for 30% (west) and 20% (east) of total observed fine aerosol concentrations. Our analysis supports bottom-up source estimates for the contiguous United States of 0.7-0.9 Tg C yr -1 from open fires (climatological) and 0.4 Tg C yr -1 from biofuel use. Biomass burning is thus an important contributor to US air quality degradation, which is likely to grow in the future.

  13. Modal structure of chemical mass size distribution in the high Arctic aerosol

    NASA Astrophysics Data System (ADS)

    Hillamo, Risto; Kerminen, Veli-Matti; Aurela, Minna; MäKelä, Timo; Maenhaut, Willy; Leek, Caroline

    2001-11-01

    Chemical mass size distributions of aerosol particles were measured in the remote marine boundary layer over the central Arctic Ocean as part of the Atmospheric Research Program on the Arctic Ocean Expedition 1996 (AOE-96). An inertial impaction method was used to classify aerosol particles into different size classes for subsequent chemical analysis. The particle chemical composition was determined by ion chromatography and by the particle-induced X-ray emission technique. Continuous particle size spectra were extracted from the raw data using a data inversion method. Clear and varying modal structures for aerosols consisting of primary sea-salt particles or of secondary particles related to dimethyl sulfide emissions were found. Concentration levels of all modes decreased rapidly when the distance from open sea increased. In the submicrometer size range the major ions found by ion chromatography were sulfate, methane sulfonate, and ammonium. They had most of the time a clear Aitken mode and one or two accumulation modes, with aerodynamic mass median diameters around 0.1 μm, 0.3 μm, and between 0.5-1.0 μm, respectively. The overall submicron size distributions of these three ions were quite similar, suggesting that they were internally mixed over most of this size range. The corresponding modal structure was consistent with the mass size distributions derived from the particle number size distributions measured with a differential mobility particle sizer. The Aitken to accumulation mode mass ratio for nss-sulfate and MSA was substantially higher during clear skies than during cloudy periods. Primary sea-salt particles formed a mode with an aerodynamic mass median diameter around 2 μm. In general, the resulting continuous mass size distributions displayed a clear modal structure consistent with our understanding of the two known major source mechanisms. One is the sea-salt aerosol emerging from seawater by bubble bursting. The other is related to

  14. Sugars in Antarctic aerosol

    NASA Astrophysics Data System (ADS)

    Barbaro, Elena; Kirchgeorg, Torben; Zangrando, Roberta; Vecchiato, Marco; Piazza, Rossano; Barbante, Carlo; Gambaro, Andrea

    2015-10-01

    The processes and transformations occurring in the Antarctic aerosol during atmospheric transport were described using selected sugars as source tracers. Monosaccharides (arabinose, fructose, galactose, glucose, mannose, ribose, xylose), disaccharides (sucrose, lactose, maltose, lactulose), alcohol-sugars (erythritol, mannitol, ribitol, sorbitol, xylitol, maltitol, galactitol) and anhydrosugars (levoglucosan, mannosan and galactosan) were measured in the Antarctic aerosol collected during four different sampling campaigns. For quantification, a sensitive high-pressure anion exchange chromatography was coupled with a single quadrupole mass spectrometer. The method was validated, showing good accuracy and low method quantification limits. This study describes the first determination of sugars in the Antarctic aerosol. The total mean concentration of sugars in the aerosol collected at the "Mario Zucchelli" coastal station was 140 pg m-3; as for the aerosol collected over the Antarctic plateau during two consecutive sampling campaigns, the concentration amounted to 440 and 438 pg m-3. The study of particle-size distribution allowed us to identify the natural emission from spores or from sea-spray as the main sources of sugars in the coastal area. The enrichment of sugars in the fine fraction of the aerosol collected on the Antarctic plateau is due to the degradation of particles during long-range atmospheric transport. The composition of sugars in the coarse fraction was also investigated in the aerosol collected during the oceanographic cruise.

  15. Field-deployable, high-resolution, time-of-flight aerosol mass spectrometer.

    PubMed

    DeCarlo, Peter F; Kimmel, Joel R; Trimborn, Achim; Northway, Megan J; Jayne, John T; Aiken, Allison C; Gonin, Marc; Fuhrer, Katrin; Horvath, Thomas; Docherty, Kenneth S; Worsnop, Doug R; Jimenez, Jose L

    2006-12-15

    The development of a new high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) is reported. The high-resolution capabilities of this instrument allow the direct separation of most ions from inorganic and organic species at the same nominal m/z, the quantification of several types of organic fragments (CxHy, CxHyOz, CxHyNp, CxHyOzNp), and the direct identification of organic nitrogen and organosulfur content. This real-time instrument is field-deployable, and its high time resolution (0.5 Hz has been demonstrated) makes it well-suited for studies in which time resolution is critical, such as aircraft studies. The instrument has two ion optical modes: a single-reflection configuration offers higher sensitivity and lower resolving power (up to approximately 2100 at m/z 200), and a two-reflectron configuration yields higher resolving power (up to approximately 4300 at m/z 200) with lower sensitivity. The instrument also allows the determination of the size distributions of all ions. One-minute detection limits for submicrometer aerosol are <0.04 microg m(-3) for all species in the high-sensitivity mode and <0.4 microg m(-3) in the high-resolution mode. Examples of ambient aerosol data are presented from the SOAR-1 study in Riverside, CA, in which the spectra of ambient organic species are dominated by CxHy and CxHyOz fragments, and different organic and inorganic fragments at the same nominal m/z show different size distributions. Data are also presented from the MIRAGE C-130 aircraft study near Mexico City, showing high correlation with independent measurements of surrogate aerosol mass concentration. PMID:17165817

  16. Demonstration of a VUV lamp photoionization source for improvedorganic speciation in an aerosol mass spectrometer

    SciTech Connect

    Northway, M.J.; Jayne, J.T.; Toohey, D.W.; Canagaratna, M.R.; Trimborn, A.; Akiyama, K-I.; Shimono, A.; Jimenez, J.L.; DeCarlo, P.F.; Wilson, K.R.; Worsnop, D.R.

    2007-10-03

    In recent years, the Aerodyne AerosolMass Spectrometer(AMS) has become a widely used tool for determining aerosol sizedistributions and chemical composition for non-refractory inorganic andorganic aerosol. The current version of the AMS uses a combination offlash thermal vaporization and 70 eV electron impact (EI) ionization.However, EI causes extensive fragmentation and mass spectra of organicaerosols are difficult to deconvolute because they are composites of theoverlapping fragmentation patterns of all species present. Previous AMSstudies have been limited to classifying organics in broad categoriessuch as oxidized and hydrocarbon-like." In this manuscript we present newefforts to gain more information about organic aerosol composition byemploying the softer technique of vacuum ultraviolet (VUV) ionization ina Time-of-Flight AMS (ToF-AMS). In our novel design a VUV lamp is placedin direct proximity of the ionization region of the AMS, with only awindow separating the lamp and the ionizer. This design allows foralternation of photoionization and electron impact ionization within thesame instrument on the timescale of minutes. Thus, the EI-basedquantification capability of the AMS is retained while improved spectralinterpretation is made possible by combined analysis of the complementaryVUV and EI ionization spectra. Photoionization and electron impactionization spectra are compared for a number of compounds including oleicacid, long chain hydrocarbons, and cigarette smoke. In general, the VUVspectra contain much less fragmentation than the EI spectra and for manycompounds the parent ion is the dominant ion in the VUV spectrum. As anexample of the usefulness of the integration of PI within the fullcapability of the ToF-AMS, size distributions and size-segregated massspectra are examined for the cigarette smoke analysis. As a finalevaluation of the new VUV module, spectra for oleic acid are compared tosimilar experiments conducted using the tunable VUV radiation

  17. Multiday production of condensing organic aerosol mass in urban and forest outflow

    NASA Astrophysics Data System (ADS)

    Lee-Taylor, J.; Hodzic, A.; Madronich, S.; Aumont, B.; Camredon, M.; Valorso, R.

    2015-01-01

    Secondary organic aerosol (SOA) production in air masses containing either anthropogenic or biogenic (terpene-dominated) emissions is investigated using the explicit gas-phase chemical mechanism generator GECKO-A. Simulations show several-fold increases in SOA mass continuing for multiple days in the urban outflow, even as the initial air parcel is diluted into the regional atmosphere. The SOA mass increase in the forest outflow is more modest (~50%) and of shorter duration (1-2 days). The multiday production in the urban outflow stems from continuing oxidation of gas-phase precursors which persist in equilibrium with the particle phase, and can be attributed to multigenerational reaction products of both aromatics and alkanes, especially those with relatively low carbon numbers (C4-15). In particular we find large contributions from substituted maleic anhydrides and multi-substituted peroxide-bicyclic alkenes. The results show that the predicted production is a robust feature of our model even under changing atmospheric conditions and different vapor pressure schemes, and contradict the notion that SOA undergoes little mass production beyond a short initial formation period. The results imply that anthropogenic aerosol precursors could influence the chemical and radiative characteristics of the atmosphere over an extremely wide region, and that SOA measurements near precursor sources may routinely underestimate this influence.

  18. Multiday production of condensing organic aerosol mass in urban and forest outflow

    NASA Astrophysics Data System (ADS)

    Lee-Taylor, J.; Hodzic, A.; Madronich, S.; Aumont, B.; Camredon, M.; Valorso, R.

    2014-07-01

    Secondary organic aerosol (SOA) production in air masses containing either anthropogenic or biogenic (terpene-dominated) emissions is investigated using the explicit gas-phase chemical mechanism generator GECKO-A. Simulations show several-fold increases in SOA mass continuing for several days in the urban outflow, even as the initial air parcel is diluted into the regional atmosphere. The SOA mass increase in the forest outflow is more modest (∼50%) and of shorter duration (1-2 days). The production in the urban outflow stems from continuing oxidation of gas-phase precursors which persist in equilibrium with the particle phase, and can be attributed to multigenerational reaction products of both aromatics and alkanes. In particular we find large contributions from substituted maleic anhydrides and multi-substituted peroxide-bicyclic alkenes. The results show that the predicted production is a robust feature of our model even under changing atmospheric conditions, and contradict the notion that SOA undergoes little mass production beyond a short initial formation period. The results imply that anthropogenic aerosol precursors could influence the chemical and radiative characteristics of the atmosphere over an extremely wide region, and that SOA measurements near precursor sources may routinely underestimate this influence.

  19. Multiday production of condensing organic aerosol mass in urban and forest outflow

    DOE PAGESBeta

    Lee-Taylor, J.; Hodzic, A.; Madronich, S.; Aumont, B.; Camredon, M.; Valorso, R.

    2015-01-16

    Secondary organic aerosol (SOA) production in air masses containing either anthropogenic or biogenic (terpene-dominated) emissions is investigated using the explicit gas-phase chemical mechanism generator GECKO-A. Simulations show several-fold increases in SOA mass continuing for multiple days in the urban outflow, even as the initial air parcel is diluted into the regional atmosphere. The SOA mass increase in the forest outflow is more modest (~50%) and of shorter duration (1–2 days). The multiday production in the urban outflow stems from continuing oxidation of gas-phase precursors which persist in equilibrium with the particle phase, and can be attributed to multigenerational reaction productsmore » of both aromatics and alkanes, especially those with relatively low carbon numbers (C4–15). In particular we find large contributions from substituted maleic anhydrides and multi-substituted peroxide-bicyclic alkenes. The results show that the predicted production is a robust feature of our model even under changing atmospheric conditions and different vapor pressure schemes, and contradict the notion that SOA undergoes little mass production beyond a short initial formation period. The results imply that anthropogenic aerosol precursors could influence the chemical and radiative characteristics of the atmosphere over an extremely wide region, and that SOA measurements near precursor sources may routinely underestimate this influence.« less

  20. Multiday production of condensing organic aerosol mass in urban and forest outflow

    DOE PAGESBeta

    Lee-Taylor, J.; Hodzic, A.; Madronich, S.; Aumont, B.; Camredon, M.; Valorso, R.

    2014-07-03

    Secondary organic aerosol (SOA) production in air masses containing either anthropogenic or biogenic (terpene-dominated) emissions is investigated using the explicit gas-phase chemical mechanism generator GECKO-A. Simulations show several-fold increases in SOA mass continuing for several days in the urban outflow, even as the initial air parcel is diluted into the regional atmosphere. The SOA mass increase in the forest outflow is more modest (∼50%) and of shorter duration (1–2 days). The production in the urban outflow stems from continuing oxidation of gas-phase precursors which persist in equilibrium with the particle phase, and can be attributed to multigenerational reaction products ofmore » both aromatics and alkanes. In particular we find large contributions from substituted maleic anhydrides and multi-substituted peroxide-bicyclic alkenes. The results show that the predicted production is a robust feature of our model even under changing atmospheric conditions, and contradict the notion that SOA undergoes little mass production beyond a short initial formation period. The results imply that anthropogenic aerosol precursors could influence the chemical and radiative characteristics of the atmosphere over an extremely wide region, and that SOA measurements near precursor sources may routinely underestimate this influence.« less

  1. Terahertz study on porosity and mass fraction of active pharmaceutical ingredient of pharmaceutical tablets.

    PubMed

    Bawuah, Prince; Tan, Nicholas; Tweneboah, Samuel Nana A; Ervasti, Tuomas; Axel Zeitler, J; Ketolainen, Jarkko; Peiponen, Kai-Erik

    2016-08-01

    In this study, terahertz time-domain spectroscopic (THz-TDS) technique has been used to ascertain the change in the optical properties, as a function of changing porosity and mass fraction of active pharmaceutical ingredient (API), of training sets of pharmaceutical tablets. Four training sets of pharmaceutical tablets were compressed with microcrystalline cellulose (MCC) excipient and indomethacin API by varying either the porosity, height, and API mass fraction or all three tablet parameters. It was observed, as far as we know, for the first time, that the THz time-domain and frequency-domain effective refractive index, as well as, the frequency-domain effective absorption coefficient both show linear correlations with the porosity and API mass fraction for training sets of real pharmaceutical tablets. We suggest that, the observed linear correlations can be useful in basic research and quality inspection of pharmaceutical tablets. Additionally, we propose a novel optical strain parameter, based on THz measurement, which yields information on the conventional strain parameter of a tablet as well as on the change of fill fraction of solid material during compression of porous pharmaceutical tablets. We suggest that the THz measurement and proposed method of data analysis, in addition to providing an efficient tool for basic research of porous media, can serve as one of the novel quality by design (QbD) implementation techniques to predict critical quality attributes (CQA) such as porosity, API mass fraction and strain of flat-faced pharmaceutical tablets before production. PMID:27288937

  2. Functional characterization of the water-soluble organic carbon of size-fractionated aerosol in the southern Mississippi Valley

    PubMed Central

    Chalbot, M.-C. G.; Brown, J.; Chitranshi, P.; da Costa, G. Gamboa; Pollock, E. D.; Kavouras, I. G.

    2016-01-01

    The chemical content of water-soluble organic carbon (WSOC) as a function of particle size was characterized in Little Rock, Arkansas in winter and spring 2013. The objectives of this study were to (i) compare the functional characteristics of coarse, fine and ultrafine WSOC and (ii) reconcile the sources of WSOC for periods when carbonaceous aerosol was the most abundant particulate component. The WSOC accounted for 5 % of particle mass for particles with δp > 0.96 μm and 10 % of particle mass for particles with δp < 0.96 μm. Non-exchangeable aliphatic (H–C), unsaturated aliphatic (H–C–C=), oxygenated saturated aliphatic (H–C–O), acetalic (O–CH–O) and aromatic (Ar–H) protons were determined by proton nuclear magnetic resonance (1H-NMR). The total non-exchangeable organic hydrogen concentrations varied from 4.1 ± 0.1 nmol m−3 for particles with 1.5 < δp < 3.0 μm to 73.9 ± 12.3 nmol m−3 for particles with δp < 0.49 μm. The molar H/C ratios varied from 0.48 ± 0.05 to 0.92 ± 0.09, which were comparable to those observed for combustion-related organic aerosol. The R–H was the most abundant group, representing about 45 % of measured total non-exchangeable organic hydrogen concentrations, followed by H–C–O (27 %) and H–C–C= (26 %). Levoglucosan, amines, ammonium and methanesulfonate were identified in NMR fingerprints of fine particles. Sucrose, fructose, glucose, formate and acetate were associated with coarse particles. These qualitative differences of 1H-NMR profiles for different particle sizes indicated the possible contribution of biological aerosols and a mixture of aliphatic and oxygenated compounds from biomass burning and traffic exhausts. The concurrent presence of ammonium and amines also suggested the presence of ammonium/aminium nitrate and sulfate secondary aerosol. The size-dependent origin of WSOC was further corroborated by the increasing δ13C abundance from −26.81 ± 0.18 ‰ for the smallest particles to

  3. Particulate matter beyond mass: recent health evidence on the role of fractions, chemical constituents and sources of emission

    PubMed Central

    Héroux, Marie-Eve; Gerlofs-Nijland, Miriam E.; Kelly, Frank J.

    2013-01-01

    Particulate matter (PM) is regulated in various parts of the world based on specific size cut offs, often expressed as 10 or 2.5 µm mass median aerodynamic diameter. This pollutant is deemed one of the most dangerous to health and moreover, problems persist with high ambient concentrations. Continuing pressure to re-evaluate ambient air quality standards stems from research that not only has identified effects at low levels of PM but which also has revealed that reductions in certain components, sources and size fractions may best protect public health. Considerable amount of published information have emerged from toxicological research in recent years. Accumulating evidence has identified additional air quality metrics (e.g. black carbon, secondary organic and inorganic aerosols) that may be valuable in evaluating the health risks of, for example, primary combustion particles from traffic emissions, which are not fully taken into account with PM2.5 mass. Most of the evidence accumulated so far is for an adverse effect on health of carbonaceous material from traffic. Traffic-generated dust, including road, brake and tire wear, also contribute to the adverse effects on health. Exposure durations from a few minutes up to a year have been linked with adverse effects. The new evidence collected supports the scientific conclusions of the World Health Organization Air Quality Guidelines and also provides scientific arguments for taking decisive actions to improve air quality and reduce the global burden of disease associated with air pollution. PMID:24304307

  4. Equilibrium uranium isotope fractionation by nuclear volume and mass-dependent processes

    NASA Astrophysics Data System (ADS)

    Schauble, E. A.

    2006-12-01

    Uranium serves as a geochemical tracer of oxidation near the Earth's surface, and is also the basis for several isotopic geochronometers. It is thus important to understand possible non-radiogenic and non-radioactive isotopic fractionation of uranium in natural systems. This study presents theoretical estimates of equilibrium uranium isotope fractionations in U-bearing molecules and complexes, calculated using first-principles computational chemistry. Ion-exchange experiments (1,2) have indicated that mass-dependent mechanisms, alone, cannot explain 238U/234U and 238U/^{235}U fractionations, so nuclear volume (i.e., field shift) fractionation effects are also considered in theoretical calculations. The results indicate that equilibrium isotopic fractionation is likely when U4+ and U6+ species equilibrate. Nuclear volume fractionation leads to higher 238U/^{235}U in U4+-bearing species, overwhelming a smaller mass- dependent fractionation in the opposite direction. The calculated net fractionation between U(H2O)_94+ and UO2Cl3(H2O)_2^- is approximately 1 per mil at 20-150°C, in agreement with earlier experiments. These results also reproduce the apparent non mass-dependent signature observed in 238U/234U relative to 238U/^{235}U. In addition to redox reactions, significant fractionation is expected between different U6+-bearing uranyl complexes (e.g., UO2(H2O)_52+, UO2(NO3)_3^-, UO2(CO3)(H2O)3). These results suggest that U-isotope composition could be used as a proxy for the oxidation state and speciation of natural waters, and that U-isotope ratios are not constant in materials formed or equilibrated at low temperatures. More generally, nuclear volume fractionations are expected to partially cancel or reverse mass-dependent fractionations caused by redox transitions among the high oxidation states (≥+2) of lanthanides, actinides, and heavy transition elements. References: 1. Nomura, Higuchi and Fujii, 1996, J. Am. Chem. Soc., v. 118, p. 9127-9130. 2. Bigeleisen

  5. Aerosol characterization over the southeastern United States using high-resolution aerosol mass spectrometry: spatial and seasonal variation of aerosol composition and sources with a focus on organic nitrates

    NASA Astrophysics Data System (ADS)

    Xu, L.; Suresh, S.; Guo, H.; Weber, R. J.; Ng, N. L.

    2015-07-01

    We deployed a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and an Aerosol Chemical Speciation Monitor (ACSM) to characterize the chemical composition of submicron non-refractory particulate matter (NR-PM1) in the southeastern USA. Measurements were performed in both rural and urban sites in the greater Atlanta area, Georgia (GA), and Centreville, Alabama (AL), for approximately 1 year as part of Southeastern Center for Air Pollution and Epidemiology study (SCAPE) and Southern Oxidant and Aerosol Study (SOAS). Organic aerosol (OA) accounts for more than half of NR-PM1 mass concentration regardless of sampling sites and seasons. Positive matrix factorization (PMF) analysis of HR-ToF-AMS measurements identified various OA sources, depending on location and season. Hydrocarbon-like OA (HOA) and cooking OA (COA) have important, but not dominant, contributions to total OA in urban sites (i.e., 21-38 % of total OA depending on site and season). Biomass burning OA (BBOA) concentration shows a distinct seasonal variation with a larger enhancement in winter than summer. We find a good correlation between BBOA and brown carbon, indicating biomass burning is an important source for brown carbon, although an additional, unidentified brown carbon source is likely present at the rural Yorkville site. Isoprene-derived OA factor (isoprene-OA) is only deconvolved in warmer months and contributes 18-36 % of total OA. The presence of isoprene-OA factor in urban sites is more likely from local production in the presence of NOx than transport from rural sites. More-oxidized and less-oxidized oxygenated organic aerosol (MO-OOA and LO-OOA, respectively) are dominant fractions (47-79 %) of OA in all sites. MO-OOA correlates well with ozone in summer but not in winter, indicating MO-OOA sources may vary with seasons. LO-OOA, which reaches a daily maximum at night, correlates better with estimated nitrate functionality from organic nitrates than total nitrates. Based

  6. Polar and non-polar organic aerosols from large-scale agricultural-waste burning emissions in Northern India: Implications to organic mass-to-organic carbon ratio.

    PubMed

    Rajput, Prashant; Sarin, M M

    2014-05-01

    This study focuses on characteristics of organic aerosols (polar and non-polar) and total organic mass-to-organic carbon ratio (OM/OC) from post-harvest agricultural-waste (paddy- and wheat-residue) burning emissions in Northern India. Aerosol samples from an upwind location (Patiala: 30.2°N, 76.3°E) in the Indo-Gangetic Plain were analyzed for non-polar and polar fractions of organic carbon (OC1 and OC2) and their respective mass (OM1 and OM2). On average, polar organic aerosols (OM2) contribute nearly 85% of the total organic mass (OM) from the paddy- and wheat-residue burning emissions. The water-soluble-OC (WSOC) to OC2 ratio, within the analytical uncertainty, is close to 1 from both paddy- and wheat-residue burning emissions. However, temporal variability and relatively low WSOC/OC2 ratio (Av: 0.67±0.06) is attributed to high moisture content and poor combustion efficiency during paddy-residue burning, indicating significant contribution (∼30%) of aromatic carbon to OC2. The OM/OC ratio for non-polar (OM1/OC1∼1.2) and polar organic aerosols (OM2/OC2∼2.2), hitherto unknown for open agricultural-waste burning emissions, is documented in this study. The total OM/OC ratio is nearly identical, 1.9±0.2 and 1.8±0.2, from paddy- and wheat-residue burning emissions. PMID:24331033

  7. From Regional Cloud-Albedo to a Global Albedo Footprint - Studying Aerosol Effects on the Radiation Budget Using the Relation Between Albedo and Cloud Fraction

    NASA Astrophysics Data System (ADS)

    Bender, F.; Engström, A.; Karlsson, J.; Wood, R.; Charlson, R. J.

    2015-12-01

    Earth's albedo is the primary determinant of the amount of energy absorbed by the Earth-atmosphere system. The main factor controlling albedo is the amount of clouds present, but aerosols can affect and alter both clear-sky and cloudy-sky reflectance. How albedo depends on cloud fraction and how albedo varies at a given cloud fraction and a given cloud water content, reveals information about these aerosol effects on the radiation budget. Hence, the relation between total albedo and cloud fraction can be used for illustration and quantification of aerosol effects, and as a diagnostic tool, to test model performance. Here, we show examples of the utilisation of this relation focusing on satellite observations from CERES and MODIS on Aqua, as well as from Calipso and CloudSat, and performing comparisons with climate models on the way: In low-cloud regions in the subtropics, we find that climate models well represent a near-constant regional cloud albedo, and this representation has improved from CMIP3 to CMIP5. CMIP5 models indicate more reflective clouds in present-day climate than pre-industrial, as a result of increased aerosol burdens. On monthly mean time scale, models are found to over-estimate the regional cloud-brightening due to aerosols. On the global scale we find an increasing cloud albedo with increasing cloud fraction - a relation that is very well defined in observations, and less so in CMIP5 models. Cloud brightening from pre-industrial to present day is also seen on global scale. Further, controlling for both cloud fraction and cloud water content we can trace small variations in albedo, or perturbations of solar reflectivity, that create a near-global coherent geographical pattern that is consistent with aerosol impacts on climate, with albedo enhancement in regions dominant of known aerosol sources and suppression of albedo in regions associated with high rates of aerosol removal (deduced using CloudSat precipitation estimates). This mapping can be

  8. Iron-Isotopic Fractionation Studies Using Multiple Collector Inductively Coupled Plasma Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Anbar, A. D.; Zhang, C.; Barling, J.; Roe, J. E.; Nealson, K. H.

    1999-01-01

    The importance of Fe biogeochemistry has stimulated interest in Fe isotope fractionation. Recent studies using thermal ionization mass spectrometry (TIMS) and a "double spike" demonstrate the existence of biogenic Fe isotope effects. Here, we assess the utility of multiple-collector inductively-coupled plasma mass spectrometry(MC-ICP-MS) with a desolvating sample introduction system for Fe isotope studies, and present data on Fe biominerals produced by a thermophilic bacterium. Additional information is contained in the original extended abstract.

  9. Surface Chemical Composition of Size-fractionated Urban Walkway Aerosols Determined by XPS and ToF-SIMS

    NASA Astrophysics Data System (ADS)

    Wenjuan, Cheng; Lu-Tao, Weng; Yongjie, Li; Arthur, Lau; Chak, Chan; Chi-Ming, Chan

    2013-04-01

    In this study, aerosol particles with sizes ranging from 0.056 to 10 ?m were collected using a ten-stage impactor sampler (MOUDI) from a busy walkway of Hong Kong. The aerosol samples of each stage were examined with X-ray photoelectron spectroscopy (XPS). Size dependent distributions of the detected six key elements (N, S, Ca, Si, O, and C) were revealed together with the chemical states of N, S and C. The results indicated that aliphatic hydrocarbons were the dominant species on the surface of all particles while a small portion of graphitic carbon (due to elemental and aromatic hydrocarbons) was also detected on the surface of the particles with sizes ranging from 0.056 to 0.32 ?m. Organic oxygen- and nitrogen-containing surface groups as well as sulfates were more abundant on the surface of the particles with sizes ranging from 0.32 to 1 μm. Organic oxygen- and nitrogen-containing surface groups as well as sulfates were more abundant on the surface of the particles with sizes ranging from 0.32 to 1 μm. Inorganic salts and nitrates were found in coarse-mode particles. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used for detailed surface and near surface composition analysis. Principal component analysis (PCA) of the ToF-SIMS spectra confirmed the XPS results that aromatic hydrocarbons were associated with the nucleation-mode particles. Aliphatic hydrocarbons with O- and N-containing functional groups were associated with accumulation-mode particles and inorganic salts were related to the coarse-mode particles. Depth-profiling experiments were performed on three specific sets of samples (nucleation-, accumulation- and coarse-mode particles) to study their near-surface structures. It showed that organic compounds were concentrated on the very top surface of the coarse-mode particles with inorganics in the core. The accumulation-mode particles had thick coatings of diverse organic compositions. The nucleation-mode particles, which contained

  10. In situ observations of aerosol and chlorine monoxide after the 1991 eruption of Mount Pinatubo - Effect of reactions on sulfate aerosol

    NASA Technical Reports Server (NTRS)

    Wilson, J. C.; Jonsson, H. H.; Brock, C. A.; Toohey, D. W.; Avallone, L. M.; Baumgardner, D.; Dye, J. E.; Poole, L. R.; Woods, D. C.; Decoursey, R. J.

    1993-01-01

    Highly resolved aerosol size distributions measured from high-altitude aircraft can be used to describe the effect of the 1991 eruption of Mount Pinatubo on the stratospheric aerosol. In some air masses, aerosol mass mixing ratios increased by factors exceeding 100 and aerosol surface area concentrations increased by factors of 30 or more. Increases in aerosol surface area concentration were accompanied by increases in chlorine monoxide at mid-latitudes when confounding factors were controlled. This observation supports the assertion that reactions occurring on the aerosol can increase the fraction of stratospheric chlorine that occurs in ozone-destroying forms.

  11. High-Resolution Desorption Electrospray Ionization Mass Spectrometry for Chemical Characterization of Organic Aerosols

    SciTech Connect

    Laskin, Julia; Laskin, Alexander; Roach, Patrick J.; Slysz, Gordon W.; Anderson, Gordon A.; Nizkorodov, Serguei; Bones, David L.; Nguyen, Lucas

    2010-03-01

    Characterization of the chemical composition and chemical transformations of secondary organic aerosol (SOA) is both a major challenge and the area of greatest uncertainty in current aerosol research. This study presents the first application of desorption electrospray ionization combined with high-resolution mass spectrometry (DESI-MS) for detailed chemical characterization and studies of chemical aging of OA collected on Teflon substrates. DESI-MS offers unique advantages both for detailed characterization of chemically labile components in OA that cannot be detected using more traditional electrospray ionization mass spectrometry (ESI-MS) and for studying chemical aging of OA. DESI-MS enables rapid characterization of OA samples collected on substrates by eliminating the sample preparation stage. In addition, it enables detection and structural characterization of chemically labile molecules in OA samples by minimizing the residence time of analyte in the solvent. SOA produced by the ozonolysis of limonene (LSOA) was allowed to react with gaseous ammonia. Chemical aging resulted in measurable changes in the optical properties of LSOA observed using UV- visible spectroscopy. DESI-MS combined with tandem mass spectrometry experiments (MS/MS) enabled identification of species in aged LSOA responsible for absorption of the visible light. Detailed analysis of the experimental data allowed us to identify chemical changes induced by reactions of LSOA constituents with ammonia and distinguish between different mechanisms of chemical aging.

  12. Mass-independent fractionation of oxygen isotopes during thermal decomposition of carbonates

    PubMed Central

    Miller, Martin F.; Franchi, Ian A.; Thiemens, Mark H.; Jackson, Teresa L.; Brack, André; Kurat, Gero; Pillinger, Colin T.

    2002-01-01

    Nearly all chemical processes fractionate 17O and 18O in a mass-dependent way relative to 16O, a major exception being the formation of ozone from diatomic oxygen in the presence of UV radiation or electrical discharge. Investigation of oxygen three-isotope behavior during thermal decomposition of naturally occurring carbonates of calcium and magnesium in vacuo has revealed that, surprisingly, anomalous isotopic compositions are also generated during this process. High-precision measurements of the attendant three-isotope fractionation line, and consequently the magnitude of the isotopic anomaly (Δ17O), demonstrate that the slope of the line is independent of the nature of the carbonate but is controlled by empirical factors relating to the decomposition procedure. For a slope identical to that describing terrestrial silicates and waters (0.5247 ± 0.0007 at the 95% confidence level), solid oxides formed during carbonate pyrolysis fit a parallel line offset by −0.241 ± 0.042‰. The corresponding CO2 is characterized by a positive offset of half this magnitude, confirming the mass-independent nature of the fractionation. Slow, protracted thermolysis produces a fractionation line of shallower slope (0.5198 ± 0.0007). These findings of a 17O anomaly being generated from a solid, and solely by thermal means, provide a further challenge to current understanding of the nature of mass-independent isotopic fractionation. PMID:12167677

  13. High time-resolution chemical characterization of the water-soluble fraction of ambient aerosols with PILS-TOC-IC and AMS

    NASA Astrophysics Data System (ADS)

    Timonen, H.; Aurela, M.; Carbone, S.; Saarnio, K.; Saarikoski, S.; Mäkelä, T.; Worsnop, D. R.; Kulmala, M.; Kerminen, V.-M.; Hillamo, R.

    2010-04-01

    A particle-into-liquid sampler (PILS) was coupled with a total organic carbon analyzer (TOC) and two ion chromatographs (IC) to enable high time-resolution measurements of water-soluble ions and water-soluble organic carbon (WSOC) by a single sampling and analytical set-up. The new high time-resolution measurement system, the PILS-TOC-IC, was able to provide essential chemical and physical information about fast changes in composition, concentrations and likely sources of the water-soluble fraction of atmospheric aerosol. The concentrations of major water-soluble ions and WSOC were measured by the PILS-TOC-IC system from 25 April to 28 May 2009. The data of the PILS-TOC-IC setup was completed with the data from the High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) data measured from 25 April to 8 May 2009. The measured water-soluble particulate organic matter (WSPOM) concentration varied typically from 0.10 to 8.8 µg m-3 (on average 1.5 µg m-3). The WSPOM contributed on average 51% to particulate organic matter (POM) measured with the AMS. The correlation between the data of all the online measurement devices (AMS, PILS-TOC-IC, semicontinous EC/OC carbon analyzer and TEOM) was excellent. For sulfate, nitrate and ammonium the correlations between the PILS-TOC-IC and AMS were 0.93, 0.96 and 0.96, respectively. The correlation between WSPOM and POM was also strong (r=0.88). The identified sources of WSPOM were long-range transported biomass burning and secondary organic aerosol (SOA) formation. The WSPOM/POM-ratio followed the trends of the ambient daytime temperature. The temperature dependency of the WSPOM/POM-ratio suggest that in the absence of emissions from biomass burning, the SOA formation was the prevailing source for WSPOM. WSPOM produced in biomass burning was clearly correlated with carbon monoxide, confirming that biomass burning was producing primary WSPOM. In addition, elevated oxalate and potassium concentrations were measured

  14. Mass fractionation of noble gases in diffusion-limited hydrodynamic hydrogen escape.

    PubMed

    Zahnle, K; Kasting, J F; Pollack, J B

    1990-01-01

    Mass fractionation by hydrodynamic hydrogen escape is a promising mechanism for explaining the observed elemental and isotopic abundance patterns in terrestrial planet atmospheres. Previous work has considered only pure hydrogen winds. Here, the theory of mass fractionation by hydrogen escape is extended to atmospheres in which hydrogen is not the only major constituent. Analytical solutions are derived for cases in which all relevant atmospheric constituents escape; both analytical and numerical solutions are obtained for cases in which important heavy constituents are retained. In either case the fractionation patterns that result can differ significantly from those produced by pure hydrogen winds. Three applications of the theory are discussed: (1) The observed fractionation of terrestrial atmospheric neon with respect to mantle neon can be explained as a by-product of diffusion-limited hydrogen escape from a steam atmosphere toward the end of accretion. (2) The anomalously high Martian (SNC) 38Ar/36Ar ratio is attributed to hydrodynamic fractionation by a vigorously escaping, nearly pure hydrogen wind. (3) It is possible that the present high Martian D/H ratio was established during the same hydrodynamic escape phase that fractionated argon, but the predicted degree of D/H enrichment is sensitive to other, less well constrained parameters. PMID:11538474

  15. Chemical characterization of the inorganic fraction of aerosols and mechanisms of the neutralization of atmospheric acidity in Athens, Greece

    NASA Astrophysics Data System (ADS)

    Karageorgos, E. T.; Rapsomanikis, S.

    2007-06-01

    The PM10 mass concentration levels and inorganic chemical composition were determined on 12-h resolution sampling during August 2003 and March 2004, in the centre of Athens, Greece. The August 2003 campaign mean PM10 mass concentration, obtained by Beta Attenuation at 5 m above ground in Athinas Street, was 56 μg m-3 while the corresponding value for March 2004 was 92 μg m-3. In both campaigns the E.U. imposed daily limit of 50 μg m-3 was exceeded on several days. During the March campaign, in Athinas Street, additionally obtained DSFU-PM10 (PM10-2.5+PM2.5) gravimetric mass concentrations (mean: 121 μg m-3) in the "breathing zone", at 1.5 m above ground were significantly higher compared to the respective mean PM10 mass concentrations obtained by the same method at 25 m above ground, in a second site (AEDA; mean: 86 μg m-3) also in the centre of the city. The above findings suggest that, for a realistic estimation of the exposure of citizens to particulate matter, PM10 sampling in the "breathing zone" (1.5-3 m above ground) is necessary. Such data are presented for the first time for the centre of Athens. In both campaigns, calcium was found to be the predominant component of the coarse fraction while crust-related aluminosilicates and iron were the other major components. The above elements constitute the most important components of the fine fraction, together with the predominant sulphur. All toxic metals were found in concentrations below the established air quality limits, and most of them in lower concentrations compared to older studies. Lead in particular, appeared mostly in the fine fraction and in very low concentrations compared to studies dating more than a decade back. The predominant ions of the coarse fraction have been found to be Ca2+, NO3-, Na+ and Cl-, while SO42-, Ca2+ and NH4+ were the major ionic components of the fine fraction. In the fine particles, a low molar ratio of NH4+/SO42- indicated an ammonium-poor ambient air, and together

  16. Iron and nickel isotopic mass fractionation in deep-sea spherules

    NASA Technical Reports Server (NTRS)

    Davis, Andrew M.; Brownlee, Donald E.

    1993-01-01

    Magnetite-wuestite spherules collected from deep-sea sediments are thought to have originally been Fe-Ni metal particles at the top of the atmosphere that were oxidized and melted during entry into the earth's atmosphere. Some likely sources for the metal particles are Fe-Ni interplanetary dust particles (IDP's) and metal or sulfide from stony IDP's that separated after melting. Davis et al. reported that four of these spherules are enriched in the heavy isotopes of iron, with enrichments of 8-23%/amu. We have developed a technique for analysis of both iron and nickel isotopes on the same ion microprobe spot and have applied this technique to a number of deep-sea spherules in order to better understand the processes leading to isotopic mass fractionation. Eight spherules show iron and nickel isotopic mass fractionation, with iron and nickel enriched in the heavy isotopes by 10-19%/amu and 4-32%/amu, respectively. If the mass fractionations are due to Rayleigh fractionation during evaporation, these spherules lost 76-94% of their original mass. We have analyzed the four magnetite-wuestite spherules for which iron isotopic data were reported by Davis et al. as well as four new spherules.

  17. Mass Spectral Observations of Submicron Aerosol Particles and Production of Secondary Organic Aerosol at an Anthropogenically Influenced Site during the Wet Season of GoAmazon2014

    NASA Astrophysics Data System (ADS)

    de Sá, S. S.; Palm, B. B.; Campuzano Jost, P.; Day, D. A.; Hu, W.; Newburn, M. K.; Ferreira De Brito, J.; Artaxo, P.; Shilling, J. E.; Souza, R. A. F. D.; Manzi, A. O.; Alexander, M. L.; Jimenez, J. L.; Martin, S. T.

    2014-12-01

    As part of GoAmazon2014, a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was deployed to characterize the composition, size, and spectral markers present in submicron atmospheric aerosol particles at a site downwind of Manaus, Brazil, in the central Amazon basin. The focus was on the influence of biogenic-anthropogenic interactions on the measured aerosol particles, especially as related to the formation of secondary organic aerosol (SOA). Through a combination of meteorology, emissions, and chemistry, the research site was affected by biogenic emissions from the tropical rainforest that were periodically mixed with urban outflow from the Manaus metropolitan area. Results from the first intensive operation period, from 1 February to 31 March 2014, show that for the wet season the PM1 mass concentration had typical values on order of 1 to 2 μg/m3. The organic species were dominant, followed by sulfate. The mass-diameter distribution of the particle population had a prevailing mode between 300 and 400 nm (vacuum aerodynamic diameter, dva), and at times a smaller mode at finer size was also present. Highly oxidized organic material was frequently observed, characterized by a dominant peak at m/z 44. There was a diel trend in the elemental oxygen-to-carbon (O:C) ratio peaking in the afternoon. The analysis of the results aims at delineating the anthropogenic impact on the measurements. Multivariate statistical analysis by positive-matrix factorization (PMF) is applied to the time series of organic particle mass spectra. The factors and their loadings provide information on the relative and time-varying contributions of different sources and processes affecting the organic component of the aerosol particle phase. Relationships between AMS results and measurements from co-located instruments that provide information on anthropogenic and biogenic gas and particle tracers are investigated, toward the goal of improving the understanding of

  18. Dry Deposition of Fine Aerosol Nitrogen to an Agricultural Field Measured by Eddy-Correlation Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Gonzales, D. A.; Allen, J. O.

    2005-12-01

    In urban areas high emissions of reactive nitrogen species cause an increase in atmospheric aerosol nitrogen formation and deposition. This nitrogen is eventually removed from the atmosphere by wet or dry deposition, with dry deposition often accounting for more than half of the total deposition of particulate nitrate. Total N deposition is not adequately characterized, in part because dry deposition is difficult to measure or model. For example measured fine particle deposition to a forest canopy differs from predicted values by an order of magnitude. The eddy-correlation technique is a micrometeorological method used to directly measure fluxes from measurements made above the surface. Eddy-correlation mass spectrometry (ECMS) has been developed to directly measure aerosol particle deposition velocities from fast response aerosol concentration and wind velocity measurements. Using an Aerodyne Aerosol Mass Spectrometer (AMS), the size and composition of ambient aerosols were measured at 10~Hz. The AMS signal is proportional to non-refractory PM1.0 mass. Aerosol deposition fluxes for a given averaging period are then calculated directly as the covariance of the vertical wind velocity with the AMS signal (F = -\\overline{w'S'}). A field study was conducted to measure aerosol nitrogen dry deposition to an agricultural field immediately downwind of the Phoenix metropolitan area using eddy-correlation mass spectrometry. The study was supplemented with aerosol composition measurements including bulk deposition collectors and filter bank samplers. Here we compare the results of the flux estimates from bulk collection with inferential measurements (filter samples and modeled deposition velocities) and direct micrometeorological measurements (ECMS) in order to improve nitrogen deposition estimates.

  19. Dry Deposition of Fine Aerosol Nitrogen to an Agricultural Field Measured by Eddy-Correlation Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Gonzales, D. A.; Allen, J. O.; Smith, K. A.; Hope, D.

    2004-12-01

    In urban areas high emissions of reactive nitrogen species cause an increase in atmospheric aerosol nitrogen formation and deposition. This nitrogen is eventually removed from the atmosphere by wet or dry deposition, with dry deposition often accounting for more than half of the total deposition of particulate nitrate (Lovett, 1994). Total N deposition is not adequately characterized, in part because dry deposition is difficult to measure or model. For example measured fine particle deposition to a forest canopy differs from predicted values by an order of magnitude (Gallagher et al., 1997). The eddy-correlation technique is a micrometeorological method used to directly measure fluxes from measurements made above the surface (Wesely and Hicks, 2000). Eddy-correlation mass spectrometry (ECMS) has been developed to directly measure aerosol particle deposition velocities from fast response aerosol concentration and wind velocity measurements. Using an Aerodyne Aerosol Mass Spectrometer (AMS) (Jayne et al., 2000), the size and composition of ambient aerosols is measured at a high frequency. The AMS signal is proportional to non-refractory PM1.0 mass. Aerosol deposition fluxes for a given averaging period are then calculated directly as the covariance of the vertical wind velocity with the AMS signal (F = -/line{w'S'}). A field study was conducted to measure aerosol nitrogen dry deposition to an agricultural field immediately downwind of the Phoenix metropolitan area using eddy-correlation mass spectrometry. The study was supplemented with aerosol composition measurements including bulk deposition collectors and filter bank samplers. Bulk deposition samples and 24-hour filter samples were analyzed for ammonia and nitrogen. Here we compare the results of the flux estimates from bulk collection with inferential measurements (filter samples and modeled deposition velocities) and direct micrometeorological measurements (ECMS) in order to improve N deposition estimates.

  20. Extensive aerosol optical properties and aerosol mass related measurements during TRAMP/TexAQS 2006 - Implications for PM compliance and planning

    NASA Astrophysics Data System (ADS)

    Wright, Monica E.; Atkinson, Dean B.; Ziemba, Luke; Griffin, Robert; Hiranuma, Naruki; Brooks, Sarah; Lefer, Barry; Flynn, James; Perna, Ryan; Rappenglück, Bernhard; Luke, Winston; Kelley, Paul

    2010-10-01

    Extensive aerosol optical properties, particle size distributions, and Aerodyne quadrupole aerosol mass spectrometer measurements collected during TRAMP/TexAQS 2006 were examined in light of collocated meteorological and chemical measurements. Much of the evident variability in the observed aerosol-related air quality is due to changing synoptic meteorological situations that direct emissions from various sources to the TRAMP site near the center of the Houston-Galveston-Brazoria (HGB) metropolitan area. In this study, five distinct long-term periods have been identified. During each of these periods, observed aerosol properties have implications that are of interest to environmental quality management agencies. During three of the periods, long range transport (LRT), both intra-continental and intercontinental, appears to have played an important role in producing the observed aerosol. During late August 2006, southerly winds brought super-micron Saharan dust and sea salt to the HGB area, adding mass to fine particulate matter (PM 2.5) measurements, but apparently not affecting secondary particle growth or gas-phase air pollution. A second type of LRT was associated with northerly winds in early September 2006 and with increased ozone and sub-micron particulate matter in the HGB area. Later in the study, LRT of emissions from wildfires appeared to increase the abundance of absorbing aerosols (and carbon monoxide and other chemical tracers) in the HGB area. However, the greatest impacts on Houston PM 2.5 air quality are caused by periods with low-wind-speed sea breeze circulation or winds that directly transport pollutants from major industrial areas, i.e., the Houston Ship Channel, into the city center.

  1. Sources and composition of submicron organic mass in marine aerosol particles

    SciTech Connect

    Frossard, Amanda A.; Russell, Lynn M.; Burrows, Susannah M.; Elliott, Scott M.; Bates, Timothy S.; Quinn, Patricia K.

    2014-11-27

    Recent studies have proposed a variety of interpretations of the sources and composition of atmospheric marine aerosol particles (aMA) based on a range of physical and chemical measurements collected during open-ocean research cruises. To investigate the processes that affect marine organic particles, this study uses the characteristic functional group composition (from Fourier transform infrared (FTIR) spectroscopy) of aMAP from five ocean regions to show that: (i) The organic functional group composition of aMAP that can be identified as atmospheric primary marine (ocean-derived) aerosol (aPMA) is 65±12% hydroxyl, 21±9% alkane, 6±6% amine, and 7±8% carboxylic acid functional groups. Contributions from photochemical reactions add carboxylic acid groups (15%-25%), shipping effluent in seawater and ship emissions add additional alkane groups (up to 70%), and coastal emissions mix in alkane and carboxylic acid groups from coastal pollution sources. (ii) The organic composition of aPMA is nearly identical to model generated primary marine aerosol particles (gPMA) from bubbled seawater (55% hydroxyl, 32% alkane, and 13% amine functional groups), indicating that its overall functional group composition is the direct consequence of the organic constituents of the seawater source. (iii) While the seawater organic functional group composition was nearly invariant across all three ocean regions studied, the gPMA alkane group fraction increased with chlorophyll-a concentrations (r = 0.79). gPMA from productive seawater had a larger fraction of alkane functional groups (35%) compared to gPMA from non-productive seawater (16%), likely due to the presence of surfactants in productive seawater that stabilize the bubble film and lead to preferential drainage of the more soluble (lower alkane group fraction) organic components. gPMA has a hydroxyl group absorption peak location characteristic of monosaccharides and disaccharides, where the seawater OM hydroxyl group peak

  2. Sources and composition of submicron organic mass in marine aerosol particles

    DOE PAGESBeta

    Frossard, Amanda A.; Russell, Lynn M.; Burrows, Susannah M.; Elliott, Scott M.; Bates, Timothy S.; Quinn, Patricia K.

    2014-11-27

    Recent studies have proposed a variety of interpretations of the sources and composition of atmospheric marine aerosol particles (aMA) based on a range of physical and chemical measurements collected during open-ocean research cruises. To investigate the processes that affect marine organic particles, this study uses the characteristic functional group composition (from Fourier transform infrared (FTIR) spectroscopy) of aMAP from five ocean regions to show that: (i) The organic functional group composition of aMAP that can be identified as atmospheric primary marine (ocean-derived) aerosol (aPMA) is 65±12% hydroxyl, 21±9% alkane, 6±6% amine, and 7±8% carboxylic acid functional groups. Contributions from photochemicalmore » reactions add carboxylic acid groups (15%-25%), shipping effluent in seawater and ship emissions add additional alkane groups (up to 70%), and coastal emissions mix in alkane and carboxylic acid groups from coastal pollution sources. (ii) The organic composition of aPMA is nearly identical to model generated primary marine aerosol particles (gPMA) from bubbled seawater (55% hydroxyl, 32% alkane, and 13% amine functional groups), indicating that its overall functional group composition is the direct consequence of the organic constituents of the seawater source. (iii) While the seawater organic functional group composition was nearly invariant across all three ocean regions studied, the gPMA alkane group fraction increased with chlorophyll-a concentrations (r = 0.79). gPMA from productive seawater had a larger fraction of alkane functional groups (35%) compared to gPMA from non-productive seawater (16%), likely due to the presence of surfactants in productive seawater that stabilize the bubble film and lead to preferential drainage of the more soluble (lower alkane group fraction) organic components. gPMA has a hydroxyl group absorption peak location characteristic of monosaccharides and disaccharides, where the seawater OM hydroxyl group

  3. DDA Computations of Porous Aggregates with Forsterite Crystals: Effects of Crystal Shape and Crystal Mass Fraction

    NASA Technical Reports Server (NTRS)

    Wooden, Diane H.; Lindsay, Sean S.; Harker, David; Woodward, Charles; Kelley, Michael S.; Kolokolova, Ludmilla

    2015-01-01

    Porous aggregate grains are commonly found in cometary dust samples and are needed to model cometary IR spectral energy distributions (SEDs). Models for thermal emissions from comets require two forms of silicates: amorphous and crystalline. The dominant crystal resonances observed in comet SEDs are from Forsterite (Mg2SiO4). The mass fractions that are crystalline span a large range from 0.0 < or = fcrystal < or = 0.74. Radial transport models that predict the enrichment of the outer disk (>25 AU at 1E6 yr) by inner disk materials (crystals) are challenged to yield the highend-range of cometary crystal mass fractions. However, in current thermal models, Forsterite crystals are not incorporated into larger aggregate grains but instead only are considered as discrete crystals. A complicating factor is that Forsterite crystals with rectangular shapes better fit the observed spectral resonances in wavelength (11.0-11.15 microns, 16, 19, 23.5, 27, and 33 microns), feature asymmetry and relative height (Lindley et al. 2013) than spherically or elliptically shaped crystals. We present DDA-DDSCAT computations of IR absorptivities (Qabs) of 3 micron-radii porous aggregates with 0.13 < or = fcrystal < or = 0.35 and with polyhedral-shaped Forsterite crystals. We can produce crystal resonances with similar appearance to the observed resonances of comet Hale- Bopp. Also, a lower mass fraction of crystals in aggregates can produce the same spectral contrast as a higher mass fraction of discrete crystals; the 11micron and 23 micron crystalline resonances appear amplified when crystals are incorporated into aggregates composed otherwise of spherically shaped amorphous Fe-Mg olivines and pyroxenes. We show that the optical properties of a porous aggregate is not linear combination of its monomers, so aggregates need to be computed. We discuss the consequence of lowering comet crystal mass fractions by modeling IR SEDs with aggregates with crystals, and the implications for radial

  4. Fullerene Soot in Eastern China Air: Results from Soot Particle-Aerosol Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Wang, J.; Ge, X.; Chen, M.; Zhang, Q.; Yu, H.; Sun, Y.; Worsnop, D. R.; Collier, S.

    2015-12-01

    In this work, we present for the first time, the observation and quantification of fullerenes in ambient airborne particulate using an Aerodyne Soot Particle - Aerosol Mass Spectrometer (SP-AMS) deployed during 2015 winter in suburban Nanjing, a megacity in eastern China. The laser desorption and electron impact ionization techniques employed by the SP-AMS allow us to differentiate various fullerenes from other aerosol components. Mass spectrum of the identified fullerene soot is consisted by a series of high molecular weight carbon clusters (up to m/z of 2000 in this study), almost identical to the spectral features of commercially available fullerene soot, both with C70 and C60 clusters as the first and second most abundant species. This type of soot was observed throughout the entire study period, with an average mass loading of 0.18 μg/m3, accounting for 6.4% of the black carbon mass, 1.2% of the total organic mass. Temporal variation and diurnal pattern of fullerene soot are overall similar to those of black carbon, but are clearly different in some periods. Combining the positive matrix factorization, back-trajectory and analyses of the meteorological parameters, we identified the petrochemical industrial plants situating upwind from the sampling site, as the major source of fullerene soot. In this regard, our findings imply the ubiquitous presence of fullerene soot in ambient air of industry-influenced area, especially the oil and gas production regions. This study also offers new insights into the characterization of fullerenes from other environmental samples via the advanced SP-AMS technique.

  5. Investigations of primary and secondary particulate matter of different wood combustion appliances with a high-resolution time-of-flight aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Heringa, M. F.; Decarlo, P. F.; Chirico, R.; Tritscher, T.; Dommen, J.; Weingartner, E.; Richter, R.; Wehrle, G.; Prévôt, A. S. H.; Baltensperger, U.

    2011-06-01

    rather low relative contribution at m/z 43 (f 43) to the total organic mass spectrum. The non-oxidized fragment C3H7+ has a considerable contribution at m/z 43 for the fresh OA with an increasing contribution of the oxygenated ion C2H3O+ during aging. After five hours of aging, the OA has a rather low C2H3O+ signal for a given CO2+ fraction, possibly indicating a higher ratio of acid to non-acid oxygenated compounds in wood burning OA compared to other oxygenated organic aerosol (OOA).

  6. Aerosol properties, source identification, and cloud processing in orographic clouds measured by single particle mass spectrometry on a Central European mountain site during HCCT-2010

    NASA Astrophysics Data System (ADS)

    Roth, A.; Schneider, J.; Klimach, T.; Mertes, S.; van Pinxteren, D.; Herrmann, H.; Borrmann, S.

    2015-09-01

    Cloud residues and out-of-cloud aerosol particles with diameters between 150 and 900 nm have been analysed by on-line single particle aerosol mass spectrometry during the six-week study HCCT-2010 in September/October 2010. The measurement location was the mountain Schmücke (937 m a.s.l.) in Central Germany. More than 170 000 bipolar mass spectra from out-of-cloud aerosol particles and more than 14 000 bipolar mass spectra from cloud residual particles were obtained and were classified using a fuzzy c-means clustering algorithm. Analysis of the uncertainty of the sorting algorithm was conducted on a subset of the data by comparing the clustering output with particle-by-particle inspection and classification by the operator. This analysis yielded a false classification probability between 13 and 48 %. Additionally, particle types were identified by specific marker ions. The results from the ambient aerosol analysis show that 63 % of the analysed particles belong to clusters indicating a diurnal variation, suggesting that local or regional sources dominate the aerosol, especially for particles containing soot and biomass burning particles. In the cloud residues the relative percentage of large soot-containing particles and particles containing amines was found to be increased compared to the out-of-cloud aerosol, while in general organic particles were less abundant in the cloud residues. In the case of amines this can be explained by the high solubility of the amines, while the large soot-containing particles were found to be internally mixed with inorganics, which explains their activation as cloud condensation nuclei. Furthermore, the results show that during cloud processing, both sulphate and nitrate are added to the residual particles, thereby changing the mixing state and increasing the fraction of particles with nitrate and/or sulphate. This is expected to lead to higher hygroscopicity after cloud evaporation, and therefore to an increase of the particles

  7. Aerosol properties, source identification, and cloud processing in orographic clouds measured by single particle mass spectrometry on a central European mountain site during HCCT-2010

    NASA Astrophysics Data System (ADS)

    Roth, A.; Schneider, J.; Klimach, T.; Mertes, S.; van Pinxteren, D.; Herrmann, H.; Borrmann, S.

    2016-01-01

    Cloud residues and out-of-cloud aerosol particles with diameters between 150 and 900 nm were analysed by online single particle aerosol mass spectrometry during the 6-week study Hill Cap Cloud Thuringia (HCCT)-2010 in September-October 2010. The measurement location was the mountain Schmücke (937 m a.s.l.) in central Germany. More than 160 000 bipolar mass spectra from out-of-cloud aerosol particles and more than 13 000 bipolar mass spectra from cloud residual particles were obtained and were classified using a fuzzy c-means clustering algorithm. Analysis of the uncertainty of the sorting algorithm was conducted on a subset of the data by comparing the clustering output with particle-by-particle inspection and classification by the operator. This analysis yielded a false classification probability between 13 and 48 %. Additionally, particle types were identified by specific marker ions. The results from the ambient aerosol analysis show that 63 % of the analysed particles belong to clusters having a diurnal variation, suggesting that local or regional sources dominate the aerosol, especially for particles containing soot and biomass burning particles. In the cloud residues, the relative percentage of large soot-containing particles and particles containing amines was found to be increased compared to the out-of-cloud aerosol, while, in general, organic particles were less abundant in the cloud residues. In the case of amines, this can be explained by the high solubility of the amines, while the large soot-containing particles were found to be internally mixed with inorganics, which explains their activation as cloud condensation nuclei. Furthermore, the results show that during cloud processing, both sulfate and nitrate are added to the residual particles, thereby changing the mixing state and increasing the fraction of particles with nitrate and/or sulfate. This is expected to lead to higher hygroscopicity after cloud evaporation, and therefore to an increase of

  8. Determination of the organic aerosol mass to organic carbon ratio in IMPROVE samples.

    PubMed

    El-Zanan, Hazem S; Lowenthal, Douglas H; Zielinska, Barbara; Chow, Judith C; Kumar, Naresh

    2005-07-01

    The ratio of organic mass (OM) to organic carbon (OC) in PM(2.5) aerosols at US national parks in the IMPROVE network was estimated experimentally from solvent extraction of sample filters and from the difference between PM(2.5) mass and chemical constituents other than OC (mass balance) in IMPROVE samples from 1988 to 2003. Archived IMPROVE filters from five IMPROVE sites were extracted with dichloromethane (DCM), acetone and water. The extract residues were weighed to determine OM and analyzed for OC by thermal optical reflectance (TOR). On average, successive extracts of DCM, acetone, and water contained 64%, 21%, and 15%, respectively, of the extractable OC, respectively. On average, the non-blank-corrected recovery of the OC initially measured in these samples by TOR was 115+/-42%. OM/OC ratios from the combined DCM and acetone extracts averaged 1.92 and ranged from 1.58 at Indian Gardens, AZ in the Grand Canyon to 2.58 at Mount Rainier, WA. The average OM/OC ratio determined by mass balance was 2.07 across the IMPROVE network. The sensitivity of this ratio to assumptions concerning sulfate neutralization, water uptake by hygroscopic species, soil mass, and nitrate volatilization were evaluated. These results suggest that the value of 1.4 for the OM/OC ratio commonly used for mass and light extinction reconstruction in IMPROVE is too low. PMID:15950041

  9. Constraining Aerosol Optical Models Using Ground-Based, Collocated Particle Size and Mass Measurements in Variable Air Mass Regimes During the 7-SEAS/Dongsha Experiment

    NASA Technical Reports Server (NTRS)

    Bell, Shaun W.; Hansell, Richard A.; Chow, Judith C.; Tsay, Si-Chee; Wang, Sheng-Hsiang; Ji, Qiang; Li, Can; Watson, John G.; Khlystov, Andrey

    2012-01-01

    During the spring of 2010, NASA Goddard's COMMIT ground-based mobile laboratory was stationed on Dongsha Island off the southwest coast of Taiwan, in preparation for the upcoming 2012 7-SEAS field campaign. The measurement period offered a unique opportunity for conducting detailed investigations of the optical properties of aerosols associated with different air mass regimes including background maritime and those contaminated by anthropogenic air pollution and mineral dust. What appears to be the first time for this region, a shortwave optical closure experiment for both scattering and absorption was attempted over a 12-day period during which aerosols exhibited the most change. Constraints to the optical model included combined SMPS and APS number concentration data for a continuum of fine and coarse-mode particle sizes up to PM2.5. We also take advantage of an IMPROVE chemical sampler to help constrain aerosol composition and mass partitioning of key elemental species including sea-salt, particulate organic matter, soil, non sea-salt sulphate, nitrate, and elemental carbon. Our results demonstrate that the observed aerosol scattering and absorption for these diverse air masses are reasonably captured by the model, where peak aerosol events and transitions between key aerosols types are evident. Signatures of heavy polluted aerosol composed mostly of ammonium and non sea-salt sulphate mixed with some dust with transitions to background sea-salt conditions are apparent in the absorption data, which is particularly reassuring owing to the large variability in the imaginary component of the refractive indices. Extinctive features at significantly smaller time scales than the one-day sample period of IMPROVE are more difficult to reproduce, as this requires further knowledge concerning the source apportionment of major chemical components in the model. Consistency between the measured and modeled optical parameters serves as an important link for advancing remote

  10. Mass size distributions of water-soluble inorganic and organic ions in size-segregated aerosols over metropolitan Newark in the US east coast

    NASA Astrophysics Data System (ADS)

    Zhao, Yunliang; Gao, Yuan

    2008-06-01

    To characterize the mass size distributions of water-soluble inorganic and organic ions associated with urban particulate matter, a total of 15 sets of size-segregated aerosol samples were collected by a 10-stage Micro-Orifice Uniform Deposit Impactor (MOUDI) in the urban area of Newark in New Jersey from July to December 2006. The mass concentrations of PM1.8 accounted for ∼68% of the mass concentrations of PM10. The mass concentrations of the total water-soluble ions in PM1.8 accounted for 31-81% of the mass concentrations of PM1.8. Sulfate was the dominant ion in fine particles, accounting for 31% of the PM1.8 mass with its dominant mode at 0.32-0.56 μm throughout all the samples. Nitrate size distributions were bi-modal, peaking at 0.32-0.56 and 3.2-5.6 μm, and the shift of the nitrate dominant fraction between fine and coarse modes was affected by temperature. The ratios of nitrate to PM1.8 varied significantly, 0.5-27%. The C2-C4 dicarboxylic acids accounted for 1.9±0.9% of PM1.8 mass, with oxalate being the dominant ion. The size distributions of oxalate exhibited two to four modes with the dominant one at 0.32-0.56 μm. Chloride existed in both coarse and fine modes, suggesting the influence of sea-salt aerosol and anthropogenic emissions. A crucial formation mechanism for the mass size distributions of these ions observed at this location is likely to be a combination of the gas-to-particle conversion and in-cloud/fog processing.

  11. Organic aerosol mass spectral signatures from wood-burning emissions: Influence of burning conditions and wood type

    NASA Astrophysics Data System (ADS)

    Weimer, S.; Alfarra, M. R.; Schreiber, D.; Mohr, M.; PréVôT, A. S. H.; Baltensperger, U.

    2008-05-01

    Wood-burning for domestic heating purposes is becoming more important owing to the increasing use of wood as a renewable fuel. Particle emissions from residential wood combustion contribute substantially to particulate matter during winter. An Aerodyne quadrupole aerosol mass spectrometer was used to study the variability of the mass spectra of organic aerosol particles emitted from the burning of different wood types as a function of burning conditions and burning technologies. Previously found wood-burning mass fragment markers in ambient air and for levoglucosan such as m/z 60, 73, and 29 were confirmed as a feature of wood-burning aerosol. They were enhanced during the flaming phase and reduced in the smoldering phase when burning was conducted in a small wood stove. The mass spectra during the smoldering phase were dominated by oxygenated species and exhibited a strong resemblance to the mass spectrum of fulvic acid which is used as a model compound for highly oxidized aerosol. A strong resemblance between the mass spectra of fulvic acid and organic particles emitted during wood-burning in an automatic furnace was found. In general, we found larger differences in the mass spectra between flaming and smoldering phases of one wood type than between different wood types within the same phase. Furthermore it was observed that during one experiment where white fir bark was burned the contribution of polycyclic aromatic hydrocarbons to the total organic matter was very high (˜30%) compared to other wood-burning experiments (0.4-2.2%).

  12. Performance of an improved monodisperse aerosol generation interface for liquid chromatography/mass spectrometry

    SciTech Connect

    Winkler, P.C.; Perkins, D.D.; Williams, W.K.; Browner, R.F.

    1988-03-01

    An improved monodisperse aerosol generation interface for liquid chromatography/mass spectrometry interfacing (MAG-IC-LC/MS) is described. The interface has an aerodynamically superior momentum separator, which results in decreased analyte loss in passing through the interface. The interface is shown to perform well with a quadrupole mass spectrometer, in addition to earlier studies with a magnetic sector instrument. A new method of forming aerosol has been developed, which reduces the dead volume significantly over earlier designs. The performance of the interface has been evaluated by studying its capabilities for (1) generating electron impact spectra of searchable quality for selected compounds of interest, (2) operating with typical liquid chromatographic separation conditions, including reverse phase and gradient elution, and (3) providing low detection limits for both full scan and selective ion monitoring detection of a range of compounds. Studies include identification of the components of a mixture of cis and trans isomers of the thermally labile compound retinol (vitamin A) acetate. Full scan (m/z 80-350) electron impact spectra were readily obtained with 50-ng injection on-column. Detection limits for this compound were 10 ng full scan and 1 ng with selected ion monitoring. Identification of a free (nonderivatized) fatty acid mixture was also readily obtained, using a reversed-phase separation in gradient mode.

  13. Characterisation of indoor airborne particles by using real-time aerosol mass spectrometry.

    PubMed

    Dall'Osto, Manuel; Harrison, Roy M; Charpantidou, E; Loupa, G; Rapsomanikis, S

    2007-10-01

    An Aerosol Time-of-Flight Mass Spectrometer (ATOFMS; TSI 3800) was deployed to Athens (Greece) during August 2003. The instrument provides information on a polydisperse aerosol, acquiring precise aerodynamic diameter (+/-1%) within the range 0.3 to 3 mum and individual particle positive and negative mass spectral data in real time. Sampling was carried out indoors and outdoors at an office in a building on a minor road in the city centre and various outdoor and indoor sources were identified. Specific outdoor particles such as dust and carbon particles were detected in indoor air. The generation of particles from indoor sources was studied and several different types of particle were found to be present in environmental tobacco smoke (ETS): three were potassium-rich (with differing proportions of carbon) emitted directly in the exhaled mainstream smoke. Two other types arose mainly when the cigarette was left smouldering on an ash-tray. Another particle type exhibited a strong signal at m/z 84, most likely due to a nicotine fragment. The temporal trend of this specific particle type showed likely condensation of semi-volatile constituents on existing potassium-rich particles. A release of insect repellent in the room was also successfully monitored. PMID:17628640

  14. Measurements of secondary organic aerosol formed from OH-initiated photo-oxidation of isoprene using online photoionization aerosol mass spectrometry.

    PubMed

    Fang, Wenzheng; Gong, Lei; Zhang, Qiang; Cao, Maoqi; Li, Yuquan; Sheng, Liusi

    2012-04-01

    Isoprene is a significant source of atmospheric organic aerosol; however, the secondary organic aerosol (SOA) formation and involved chemical reaction pathways have remained to be elucidated. Recent works have shown that the photo-oxidation of isoprene leads to form SOA. In this study, the chemical composition of SOA from the OH-initiated photo-oxidation of isoprene, in the absence of seed aerosols, was investigated through the controlled laboratory chamber experiments. Thermal desorption/tunable vacuum-ultraviolet photoionization time-of-flight aerosol mass spectrometry (TD-VUV-TOF-PIAMS) was used in conjunction with the environmental chamber to study SOA formation. The mass spectra obtained at different photon energies and the photoionization efficiency (PIE) spectra of the SOA products can be obtained in real time. Aided by the ionization energies (IE) either from the ab initio calculations or the literatures, a number of SOA products were proposed. In addition to methacrolein, methyl vinyl ketone, and 3-methyl-furan, carbonyls, hydroxycarbonyls, nitrates, hydroxynitrates, and other oxygenated compounds in SOA formed in laboratory photo-oxiadation experiments were identified, some of them were investigated for the first time. Detailed chemical identification of SOA is crucial for understanding the photo-oxidation mechanisms of VOCs and the eventual formation of SOA. Possible reaction mechanisms will be discussed. PMID:22397593

  15. Aerosol composition and properties variation at the ground and over the column under different air masses advection in South Italy.

    PubMed

    Pavese, G; Lettino, A; Calvello, M; Esposito, F; Fiore, S

    2016-04-01

    Aerosol composition and properties variation under the advection of different air masses were investigated, as case studies, by contemporary measurements over the atmospheric column and at the ground in a semi-rural site in South Italy. The absence of local strong sources in this area allowed to characterize background aerosol and to compare particle mixing effects under various atmospheric circulation conditions. Aerosol optical depth (AOD) and Ǻngström parameters from radiometric measurements allowed the detection and identification of polluted, dust, and volcanic atmospheric conditions. AODs were the input for a suitable model to evaluate the columnar aerosol composition, according to six main atmospheric components (water-soluble, soot, sea salt accumulation, sea salt coarse, mineral dus,t and biological). Scanning electron microscope (SEM) analysis of particulate sampled with a 13-stage impactor at the ground showed not only fingerprints typical of the different air masses but also the effects of transport and aging on atmospheric particles, suggesting processes that changed their chemical and optical properties. Background columnar aerosol was characterized by 72% of water-soluble and soot, in agreement with ground-based findings that highlighted 60% of contribution from anthropogenic carbonate particles and soot. In general, a good agreement between ground-based and columnar results was observed. Under the advection of trans-boundary air masses, water-soluble and soot were always present in columnar aerosol, whereas, in variable percentages, sea salt and mineral particles characterized both dust and volcanic conditions. At the ground, sulfates characterized the amorphous matrix produced in finer stages by the evaporation of solutions of organic and inorganic aerosols. Sulfates were also one of the key players involved in heterogeneous chemical reactions, producing complex secondary aerosol, as such clay-sulfate internally mixed particle externally mixed

  16. DARK MATTER MASS FRACTION IN LENS GALAXIES: NEW ESTIMATES FROM MICROLENSING

    SciTech Connect

    Jiménez-Vicente, J.; Mediavilla, E.; Muñoz, J. A.

    2015-02-01

    We present a joint estimate of the stellar/dark matter mass fraction in lens galaxies and the average size of the accretion disk of lensed quasars based on microlensing measurements of 27 quasar image pairs seen through 19 lens galaxies. The Bayesian estimate for the fraction of the surface mass density in the form of stars is α = 0.21 ± 0.14 near the Einstein radius of the lenses (∼1-2 effective radii). The estimate for the average accretion disk size is R{sub 1/2}=7.9{sub −2.6}{sup +3.8}√(M/0.3 M{sub ⊙}) light days. The fraction of mass in stars at these radii is significantly larger than previous estimates from microlensing studies assuming quasars were point-like. The corresponding local dark matter fraction of 79% is in good agreement with other estimates based on strong lensing or kinematics. The size of the accretion disk inferred in the present study is slightly larger than previous estimates.

  17. A Miniature System for Separating Aerosol Particles and Measuring Mass Concentrations

    PubMed Central

    Liang, Dao; Shih, Wen-Pin; Chen, Chuin-Shan; Dai, Chi-An

    2010-01-01

    We designed and fabricated a new sensing system which consists of two virtual impactors and two quartz-crystal microbalance (QCM) sensors for measuring particle mass concentration and size distribution. The virtual impactors utilized different inertial forces of particles in air flow to classify different particle sizes. They were designed to classify particle diameter, d, into three different ranges: d < 2.28 μm, 2.28 μm ≤ d ≤ 3.20 μm, d > 3.20 μm. The QCM sensors were coated with a hydrogel, which was found to be a reliable adhesive for capturing aerosol particles. The QCM sensor coated with hydrogel was used to measure the mass loading of particles by utilizing its characteristic of resonant frequency shift. An integrated system has been demonstrated. PMID:22319317

  18. Simultaneous analysis of heparosan oligosaccharides by isocratic liquid chromatography with charged aerosol detection/mass spectrometry.

    PubMed

    Ji, Xiaohu; Hu, Guixin; Zhang, Qiongyan; Wang, Fengshan; Liu, Chunhui

    2016-11-01

    Uncovering the biological roles of heparosan oligosaccharides requires a simple and robust method for their separation and identification. We reported on systematic investigations of the retention behaviors of synthetic heparosan oligosaccharides on porous graphitic carbon (PGC) column by HPLC with charged aerosol detection. Oligosaccharides wer